tests/test-check-jshint.t

automation: add check that hg source directory is a repo

Synchronizing from e.g. source distributions is not yet supported.
Let's add a check so we fail with an error message indicating
such.

Differential Revision: https://phab.mercurial-scm.org/D6315

#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