fixup! stbt batch: Extract backtrace from log and show in testrun html page
Revert "(DON'T MERGE) stbt batch report: Look for runtests.py "FAIL" line instead of stbt-run's output"

This reverts commit b271bff8a4181ff82ecd0beca276815224444779.

Our private nose-style test-runner now prints this "FAIL" line in the
same format that `stbt run` does.