When switching between different branches in a VCS system, file modification date may change even though its contents isn't. For example, when switching from trunk to a branch X where the file is modified, then switching back.
As a result, if the file was opened in Emacs before the switches, and I attempt to edit it afterwards, Emacs prompts me with "... changed on disk; really edit the buffer?" even though the only thing that "changed" about it is the modification time. (To make it worse, Emacs requires _three_ confirmation to edit and save...)
Request: if Emacs detects timestamp change, let it read the file and compare it with the buffer; if they are byte-to-byte identical, just ignore the timestamp.
To reproduce: open any existing file, say 'x.txt'. Now type: