Fix `./pants server` not working with Python 3 #7458
Due to various unicode issues,
Fix unicode issues.
Also add an assertion that the argument to
Reviewers, we don't have very good integration testing for
I didn't add testing here because we need to land this fix into 1.15.0 and I don't have time (nor the knowledge) to write comprehensive tests.
Instead, I tested this out locally by running