Mountain Lion update and mercurial libraries python
On OS X - 10.8.2Installing mercurial through Python easy_install tool solved the problem
easy_install -U mercurial
I just ran into the same problem, picked a new version (mercurial-2.2.3+20120707-py2.7-macosx10.7) from the Mercurial website and now it works again.
I had a similar problem to this last night after upgrading to OX 10.9 Mavericks. I had tried brew install hg and brew update but they didn't work, as everyone's systems are different if you're running homebrew I would recommend running brew doctorto see what your particular issue is, in my case I had the following;
Warning: You have unlinked kegs in your Cellar
Leaving kegs unlinked can lead to build-trouble and cause brews that depend on those kegs to fail to run properly once built. Run
brew linkon these: mercurial
So to fix my mercurial issue I ran;
brew link --overwrite mercurial