tests/test-check-jshint.t

rust-dirstatemap: add `set_cached_mtime` helper method

This will help remove the `get_or_insert` method, which is dangerous because it
does not take the `DirstateMap` counters into account

Differential Revision: https://phab.mercurial-scm.org/D12526

#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