tests/test-abort-checkin.t

chg: allows default hg path to be overridden

Before this patch, chg will fall back to "hg" if neither CHGHG nor HG are set.
This may have trouble if the "hg" in PATH is not compatible with chg, which
can happen, for example, an old hg is installed in a virtualenv.

Since it's very hard to do a quick hg version check from chg, after discussion
in IRC with smf and marmoute, the quickest solution is to build a package with
a hardcoded absolute hg path in chg. This patch makes it possible by adding a
C macro HGPATH.

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

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > abortcommit = $abspath
  > EOF

  $ 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 ..