when is "git diff" output suitable for patch?

I assume the -C and -M, -c, and -cc options all result in diff output
that can't be correctly applied by "patch" any more?  (Would a patch to
the git-diff-files documentation warning about this be helpful?)

Someone I'm working with is having trouble applying patches that they
created with a simple "git diff".  The patches in question have some
"copy from/copy to" headers.  Should that every happen with just a plain
"git diff"?  Is this a bug in their version of git?  (They're on 1.2.4).

--b.