run-tests: make code coverage work on Python 3
This code path was obviously not tested on Python 3 because it
blew up in several places due to str/bytes mismatch.
For internal code, we normalize paths to bytes.
For code calling into `coverage`, we normalize paths to str,
which is what `coverage` seems to expect.
After this, `run-tests.py -H` works on Python 3!
Differential Revision: https://phab.mercurial-scm.org/D7133
#require test-repo jshint hg10
$ . "$TESTDIR/helpers-testrepo.sh"
run jshint on all tracked files ending in .js except vendored dependencies
$ cd "`dirname "$TESTDIR"`"
$ testrepohg locate 'set:**.js' \
> 2>/dev/null \
> | xargs jshint