tests/test-check-jshint.t

tests: suppress "Checked out 1 paths of <hash>" from modern git

test-convert-git.t is failiing since git commit 0f086e6dca (checkout:
print something when checking out paths, 2018-11-13). Suppress the new
output by disambiguating the arguments with a "--" separator.

Differential Revision: https://phab.mercurial-scm.org/D5625

#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