I recently had a number of problems with Mercurial. The cause of one of them turned out to be that Mercurial doesn't interact with MacOS X very well, so although the commit command launches an editor to request a commit message, this message never reaches mercurial.
But a more serious problem was that resolution of conflicts did not work properly, simply discarding all the work I had done. Looking at the documentation, I see that Mercurial has no built-in code for merging, but calls an external tool. It is very likely that the result of this tool (under MacOS X) also never reaches Mercurial. Does anybody know how to set up mercurial on a Mac so that it performs its basic functions correctly? And this setting up must not take hours. Larry