The mxr repository under http://mxr.mozilla.org/comm-central/ no longer seems to update, it looks like the last update was on the 9th of September. For an example compare http://hg.mozilla.org/comm-central/annotate/713c34b1a232/mailnews/imap/src/nsImapIncomingServer.cpp#l2691 to http://mxr.mozilla.org/comm-central/source/mailnews/imap/src/nsImapIncomingServer.cpp#2694. This bug here might have to do with Bug 453973, the issue has also been mentioned there a few days ago, but nothing seems to happen.
As we're heading towards 3.0b1, getting accurate mxr is pretty critical, so raising severity level.
I can clear it up, but it just messes up again after a while... I don't know if this a client.py problem, Hg problem, or mxr problem. :/
It's back, but no doubt it'll screw up again.
Probably a mercurial bug, tracked upstream here: http://www.selenic.com/mercurial/bts/issue1313
http://hg.intevation.org/mercurial/crew/rev/9f0e52e1df77 is supposed to have fixed that issue