mq: ignore subrepos (issue2499) If MQ allows modifying .hgsub or .hgsubstate in a patch, it can easily lead to an inconsistent subrepo state. This patch prevents qrefresh from adding any modifications to .hgsub or .hgsubstate to a patch. The user is warned that these files are not included in the patch. The tests test both the slightly irrational and the pathological cases.

tests: integrate test-hardlinks-safety.t into test-hardlinks.t Should make running the testsuite a bit faster. Also, test-hardlinks.t and test-hardlinks-safety.t now have enough infrastructure in common.

mq: add an '-e/--exact' option to qpush This patch adds an '--exact/-e' option to qpush that will try to push the patches in the correct location in the DAG. Specifying this option does the following: * If --move is specified, abort. It makes no sense to move a patch to the front of the queue and try to apply it to its parent, because its parent is one of the patches we just moved it in front of! * If patches are already applied, abort. We don't want patch changesets scattered throughout the DAG. * If local changes are present, abort unless --force is used, as usual. * Find the first patch we're going to push (if we're pushing multiple patches with a target or --all). * If that patch doesn't have a parent, abort, obviously. * If the parent doesn't exist in the repo, abort. Something is wrong. * Update to the parent, then continue pushing the patches as normal.

dirstate: warn on invalid parents rather than aborting This allows more graceful recovery from some mangled dirstates

code style: prefer 'is' and 'is not' tests with singletons

polib: remove unnecessary comparisons with True Submitted to upstream repository as changeset f11e0b1b37b0.

subrepo: lazier git push logic Avoids calls to git push when the revision is already known to be in the remote repository. Now, when using a read-only git subrepo, git will never need to talk to its upstream repository.