tests: cover revision conversion logic in githelp tests
There was no test involving actual conversion of option values when they
contain a git revision name (to be converted as a hg one by
hgext.githelp.convert()). Adding one. This test would fail on Python 3
without https://phab.mercurial-scm.org/D7537.
Differential Revision: https://phab.mercurial-scm.org/D7540
#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