tests: mark test-check-pyflakes.t as requiring hg1.0+ hg does not yet run with py3, so if you try: ./run-tests.py --local test-check-pyflakes.t ... it will try to run the local hg, which does not work and thus, hg locate will return no output to stdout (and stderr is sent to /dev/null). If you do: ./run-tests.py --with-hg=~/bin/hg test-check-pyflakes.t Then it should work, if your hg is new enough to have a locate command (hg0.6 does not have locate).