I'm looking into Bug#20247 <http://bugs.gnu.org#20247>, currently listed 
as a blocker for Emacs 25. From the bug report, it appears that the 
attached patch would have prevented the bug. This patch is a change to 
Emacs behavior so I'll propose it here now, and give a heads-up on the 
Emacs-devel mailing list before installing it. Comments welcome. I don't 
care myself about the behavior one way or another (I don't use desktop 
mode) and am mainly just trying to clear out the bug backlog.