Buildstream plugin output being suppressed

Summary

When debugging a plugin for BuildStream, you have to rely on output from the bst command, in order to see what is being parsed/logged as part of the pipeline. However it seems when changing the plugin source code, and even removing the artifacts cache, bst seems to suppress output.

I am having to add print statements to my plugin in order to check the output is valid, at first the print statements seemed to work, however i was getting truncated output. But after a few runs, output has been suppressed completely.

Steps to reproduce

Add a local plugin to your bst pipeline, add some print statements to plugin, run the pipeline and see if the output appears as expected.

What is the current bug behavior?

It seem bst will sometimes log the output from a plugin, then on another occasion suppress the output.

What is the expected correct behavior?

I'm not really sure, however there should be some documented way of debugging a plugin!

Relevant logs and/or screenshots

Possible fixes

Other relevant information

• BuildStream version affected: /milestone %BuildStream_v1.x

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