Last night, I installed a rawhide version of ghc 6.10.1 in place of the F10 version I had been running. I also had packages such as ghc-X11 installed at the time. When I ran "ghc-pkg list" after the update, the X11 and other such packages were no longer visible. We need to develop a mechanism to make it possible to make minor updates to ghc without requiring that all devel packages be reinstalled afterwards :-(
Oh hmm that is bad and "should not happen"...
Are you sure? I just tried in i386 f11 downgrading to f10 and back up to f11 ghc and X11 package appeared for me all along. package.conf is already marked %config(noreplace) though - I thought that should take care of it. (We should really move package.conf to /etc like debian, but I think that is another story.)