Remy says: "The script prepare-changelog will add lines about deleted methods whenever there are some red lines in the diff, whether those line are actually methods being deleted or not. And methods that are actually deleted are never detected." This is observed when changing Obj-C source files. I'm working on a patch.
rdar://problem/18459323
(Testing WebKit Bug Importer, please ignore)
Hmmm, I actually can't reproduce this. I've tried changing an Obj-C method, deleting one, and adding one, and I've gotten what looks like correct output. I'll have to sit down with Remy and try to get some reproducible steps.
*** This bug has been marked as a duplicate of bug 143897 ***