Because current version of monodevelop contains some fixes: https://bugzilla.novell.com/show_bug.cgi?id=652814
I won't add a live ebuild for fixing a bug that upstream should fix on a new release. Either the patch fixing your bug needs to be found at: https://github.com/mono/monodevelop/commits/master (I couldn't find it :-/) or upstream should be asked to release a new fixed version instead of telling people to use development versions