"git push" into a repository with a working tree normally refuses
to modify the branch that is checked out.  The command learned to
optionally do an equivalent of "git reset --hard" only when there
is no change to the working tree and the index instead, which would
be useful to "deploy" by pushing into a repository.

* js/push-to-deploy:
  t5516: more tests for receive.denyCurrentBranch=updateInstead
  receive-pack: add another option for receive.denyCurrentBranch