tests/test-abort-checkin.t

unionrepo: read-only operations on a union of two localrepos

unionrepo is just like bundlerepo without bundles.

The implementation is very similar to bundlerepo, but I don't see any obvious
way to generalize it.

Some most obvious use cases for this would be log and diff across local repos,
as a kind of preview of pulls, for instance:

  $ hg -R union:repo1+repo2 heads
  $ hg -R union:repo1+repo2 log -r REPO1REV -r REPO2REV
  $ hg -R union:repo1+repo2 log -r '::REPO1REV-::REPO2REV'
  $ hg -R union:repo1+repo2 log -r 'ancestor(REPO1REV,REPO2REV)'
  $ hg -R union:repo1+repo2 diff -r REPO1REV -r REPO2REV

This is going to be used in RhodeCode, and Bitbucket already uses something
similar. Having a core implementation would be beneficial.

  $ cat > abortcommit.py <<EOF
  > from mercurial import util
  > def hook(**args):
  >     raise util.Abort("no commits allowed")
  > def reposetup(ui, repo):
  >     repo.ui.setconfig("hooks", "pretxncommit.nocommits", hook)
  > EOF
  $ abspath=`pwd`/abortcommit.py

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH
  $ echo "abortcommit = $abspath" >> $HGRCPATH

  $ hg init foo
  $ cd foo
  $ echo foo > foo
  $ hg add foo

mq may keep a reference to the repository so __del__ will not be
called and .hg/journal.dirstate will not be deleted:

  $ hg ci -m foo
  error: pretxncommit.nocommits hook failed: no commits allowed
  transaction abort!
  rollback completed
  abort: no commits allowed
  [255]
  $ hg ci -m foo
  error: pretxncommit.nocommits hook failed: no commits allowed
  transaction abort!
  rollback completed
  abort: no commits allowed
  [255]

  $ cd ..