tests: avoid implicit conversion of str to unicode
On Python 2, str.encode('ascii') implicitly converts the string to unicode and
then back to str.
Since the converted value is a path, _bytespath can be used instead.
#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