tests: remove support for warned tests The previous changeset removed the last caller of addWarn(). So, we rip out that method and all the code related to tracking warned tests in the results system. There was even a comment saying we may want to fold warned tests into the "failed" state, which is what the previous changeset did.

contrib: add check-code rule to enforce non-use of `python` in tests

cleanup: use $PYTHON to run python in many more tests Spotted one of these, then wrote a check-code rule that caught them all. It will be the next change.

tests: enforce use of $PYTHON in tests

tests: use $PYTHON in #! so we always use the right Python

tests: sed away python #! in test-run-tests.t to avoid some upcoming insanity

tests: remove #! from primes.py in test-highlight.t It's about to be a source of trouble, but removing it changes a ton of test lines, so doing this change as a standalone commit.

keyword: use context manager for rollback locking

tests: remove WarnTest We would raise this if a test didn't return a result code. AFAICT this can only occur if there is a logic error in the test harness itself. I don't think it is worth the code complexity to distinguish this failure scenario from a regular test failure.

tests: remove unused IgnoreTest exception AFAICT its last use was removed in d839e4820da7.