this may be variation of issue3277 when XCode is not configured well, "xcodebuild -version" may run eternally. so, installation process never end. you can reproduce this by setting xcode folder path to "/". this is occured on the environment where XCode was switched from 4.2.x to 4.3.x. of course, it is definitely problem of XCode (or users). but for users, it looks like "problem of Mercurial", so I think that it should be avoided if it can.
this issue is taught from other mercurial user, so I don't know whether XCode is upgraded reasonably or not. so, it is not so cirital and should not be avoided, if such mis-configuration is rare case.
--- Bug imported by bugzilla@serpentine.com 2012-05-12 09:30 EDT --- This bug was previously known as _bug_ 3373 at http://mercurial.selenic.com/bts/issue3373
Bulk close: no activity for >2 years -> WONTFIX
Bulk change recent WONTFIX -> new, more descriptive ARCHIVED state (sorry for the spam)