ProjectJob.artifacts may return an Iterator depending upon the
value of the `streamed` argument. Consequently, mypy rejects the
program. Manually assert the result type to satisfy it.

This makes it easier to check with mypy, which is run during the build.

Fix it

See merge request !2

Separate triage and test-tracking modules

See merge request !1

Otherwise we get errors of the form

Finished executing pythonRemoveTestsDir
running install tests
ghc_triage_service/__init__.py: error:(B Duplicate module named 'ghc_triage_service' (also at './build/lib/ghc_triage_service/__init__.py')(B
ghc_triage_service/__init__.py: note:(B Are you missing an __init__.py? Alternatively, consider using --exclude to avoid checking one of them.
Found 1 error in 1 file (errors prevented further checking)(B

Avoids psycopg's bizarre exception-safety issues.