Workhorse-only change generates invalid CI YAML

In !79761 (merged), there's a small Workhorse-only change, which starts a pipeline that fails with an invalid YAML error:

Full output

'rspec system pg12 1/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 1/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 1/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 2/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 2/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 2/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 3/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 3/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 3/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 4/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 4/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 4/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 5/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 5/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 5/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 6/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 6/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 6/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 7/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 7/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 7/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 8/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 8/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 8/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 9/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 9/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 9/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 10/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 10/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 10/24' job needs 'detect-tests' job
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but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 11/24' job needs 'compile-test-assets' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12 12/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 12/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 12/24' job needs 'detect-tests' job
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but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 13/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 13/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 14/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 14/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 14/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 15/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 15/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 15/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 16/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 16/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 16/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12 17/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 17/24' job needs 'compile-test-assets' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12 18/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12 19/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12 22/24' job needs 'retrieve-tests-metadata' job
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but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12 24/24' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec system pg12 24/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 1/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12-as-if-foss 1/24' job needs 'compile-test-assets as-if-foss' job
but 'compile-test-assets as-if-foss' is not in any previous stage 'rspec system pg12-as-if-foss 1/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 2/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12-as-if-foss 2/24' job needs 'compile-test-assets as-if-foss' job
but 'compile-test-assets as-if-foss' is not in any previous stage 'rspec system pg12-as-if-foss 2/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 3/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12-as-if-foss 3/24' job needs 'compile-test-assets as-if-foss' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 4/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12-as-if-foss 4/24' job needs 'compile-test-assets as-if-foss' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 5/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12-as-if-foss 5/24' job needs 'compile-test-assets as-if-foss' job
but 'compile-test-assets as-if-foss' is not in any previous stage 'rspec system pg12-as-if-foss 5/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 6/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 7/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 11/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 12/24' job needs 'retrieve-tests-metadata' job
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but 'compile-test-assets as-if-foss' is not in any previous stage 'rspec system pg12-as-if-foss 17/24' job needs 'detect-tests' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 19/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 20/24' job needs 'retrieve-tests-metadata' job
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but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 21/24' job needs 'retrieve-tests-metadata' job
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but 'compile-test-assets as-if-foss' is not in any previous stage 'rspec system pg12-as-if-foss 23/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec system pg12-as-if-foss 24/24' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec system pg12-as-if-foss 24/24' job needs 'compile-test-assets as-if-foss' job
but 'compile-test-assets as-if-foss' is not in any previous stage 'rspec system pg12-as-if-foss 24/24' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 1/6' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 1/6' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 1/6' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 2/6' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 2/6' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 2/6' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 3/6' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 3/6' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 3/6' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 4/6' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 4/6' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 4/6' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 5/6' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 5/6' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 5/6' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 6/6' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 6/6' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 6/6' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage 'rspec-ee system pg12 geo' job needs 'retrieve-tests-metadata' job
but 'retrieve-tests-metadata' is not in any previous stage 'rspec-ee system pg12 geo' job needs 'compile-test-assets' job
but 'compile-test-assets' is not in any previous stage 'rspec-ee system pg12 geo' job needs 'detect-tests' job
but 'detect-tests' is not in any previous stage

@kwiebers mentioned this may be related to !78697 (merged). /cc @godfat-gitlab