discovery: list new remote heads in prepush() on --debug With this patch applied, Mercurial will list the hashes of new remote heads if push --debug aborts because of new remote heads (option -f/--force not set). Example: $ hg push --debug repo1 using http://example.org/repo1 http auth: user johndoe, password not set sending between command pushing to http://example.org/repo1 sending capabilities command capabilities: changegroupsubset stream=1 lookup pushkey unbundle=HG10GZ,HG10BZ,HG10UN branchmap sending heads command searching for changes common changesets up to 609edbc7853f sending branchmap command new remote heads on branch 'default' <- new output line new remote head 5862c07f53a2 <- new output line abort: push creates new remote heads on branch 'default'! (did you forget to merge? use push -f to force) Compare to without --debug (not changed by this patch, including it here for reference purposes only): $ hg push repo1 pushing to http://example.org/repo1 searching for changes abort: push creates new remote heads on branch 'default'! (did you forget to merge? use push -f to force) Motivation for this change: 'hg outgoing' may list a whole lot of benign changesets plus an odd changeset that will trigger the "new remote heads" abort. It can be hard to spot that single unwanted changeset (it may be an old forgotten experiment, lingering in the local repo). "hg log -r 'heads(outgoing())'" might be useful, but that also lists a head that may be benign on push. Inside prepush(), we already know which heads are causing troubles on 'hg push'. Why not make that info available (at least on --debug)? This would also be helpful for doing remote support, as the supporter can ask the user to paste the output of 'hg push --debug' on error and then ask further questions about the heads listed.