mercurial extensions using util.Abort() will fail when combined with recent builds of hg having this changeset:
https://www.mercurial-scm.org/repo/hg/file/a9ea2b1e5c4b/mercurial/util.py
https://www.mercurial-scm.org/repo/hg/file/a9ea2b1e5c4b/mercurial/util.py