tests/test-abort-checkin.t

convert: check for failed svn import in debugsvnlog and abort cleanly

'hg debugsvnlog' failed with a crash when using the uninitialized transport in
get_log_child if the import of the svn libraries had failed.

'convert' should never get as far as launching 'hg debugsvnlog' if the svn
libraries are missing, but by launching a subprocess there is risk that the
environment is mangled so the second import fails.

It is in principle also possible to launch the command manually.

  $ 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 ..