Repository#write_ref fails with invalid ref_path

https://sentry.gitlap.com/gitlab/gitlabcom/issues/85659/

ArgumentError: invalid ref_path "refs/environments/ANZ\\ -\\ SIT/deployments/1"
  lib/gitlab/git/repository.rb:1026:in `write_ref'
    raise ArgumentError, "invalid ref_path #{ref_path.inspect}" if ref_path.include?(' ')
  app/models/repository.rb:1060:in `create_ref'
    raw_repository.write_ref(ref_path, ref)
  lib/gitlab/metrics/instrumentation.rb:156:in `block in create_ref'
    trans.method_call_for(#{label.to_sym.inspect}).measure { super }
  lib/gitlab/metrics/method_call.rb:23:in `measure'
    retval = yield
  lib/gitlab/metrics/instrumentation.rb:156:in `create_ref'
    trans.method_call_for(#{label.to_sym.inspect}).measure { super }
...
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invalid ref_path "refs/environments/ANZ\\ -\\ SIT/deployments/1"