I get an error message whenever I try to run Mercurial after upgrading to the latest version from Homebrew. The error message prompts me to file a bug here. The full error message is: ** Unknown exception encountered with possibly-broken third-party extension mqext ** which supports versions 3.9 of Mercurial. ** Please disable mqext and try your action again. ** If that fixes the bug please report it to https://bugzilla.mozilla.org/enter_bug.cgi?product=Developer%20Services&component=General ** Python 2.7.13 (default, Jul 18 2017, 09:17:00) [GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.42)] ** Mercurial Distributed SCM (version 4.3.1) ** Extensions loaded: rebase, purge, histedit, strip, mq, mqext, pager, firefoxtree, reviewboard, push-to-try, fsmonitor, hggit Traceback (most recent call last): File "/usr/local/bin/hg", line 45, in <module> mercurial.dispatch.run() File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/dispatch.py", line 81, in run status = (dispatch(req) or 0) & 255 File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/dispatch.py", line 162, in dispatch ret = _runcatch(req) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/dispatch.py", line 302, in _runcatch return _callcatch(ui, _runcatchfunc) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/dispatch.py", line 310, in _callcatch return scmutil.callcatch(ui, func) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/scmutil.py", line 150, in callcatch return func() File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/dispatch.py", line 292, in _runcatchfunc return _dispatch(req) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/dispatch.py", line 858, in _dispatch presetupfuncs=req.prereposetups) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/hg.py", line 168, in repository peer = _peerorrepo(ui, path, create, presetupfuncs=presetupfuncs) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/extensions.py", line 322, in closure return func(*(args + a), **kw) File "/Users/jyc/.mozbuild/version-control-tools/hgext/firefoxtree/__init__.py", line 150, in peerorrepo return orig(ui, path, *args, **kwargs) File "/usr/local/Cellar/mercurial/4.3.1/lib/python2.7/site-packages/mercurial/hg.py", line 160, in _peerorrepo hook(ui, obj) File "/Users/jyc/.mozbuild/version-control-tools/hgext/firefoxtree/__init__.py", line 629, in reposetup if not isfirefoxrepo(repo): File "/Users/jyc/.mozbuild/version-control-tools/hgext/firefoxtree/__init__.py", line 145, in isfirefoxrepo return repo.opener.exists('IS_FIREFOX_REPO') AttributeError: 'firefoxtreesrepo' object has no attribute 'opener' After commenting out all of the extensions from version-control-tools in my ~/.hgrc, I am able to run hg again without error.

hg log --version gives: Mercurial Distributed SCM (version 4.3.1) (see https://mercurial-scm.org for more information) Copyright (C) 2005-2017 Matt Mackall and others This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. I'm on macOS. uname -a gives: Darwin jc-mbp-osx 16.7.0 Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64 x86_64

your version-control-tools clone needs updating - please run `mach mercurial-setup`.