Hello all,

It looks like darcs replace foo bar foo.c foo.c works in somewhat
unexpected manner:

1) darcs checks that foo.c and foo.c does not contain bar
2) darcs changes foo to bar in foo.c
3) it again tries to change foo to bar in foo.c, but finds bar and
barfs like this

darcs failed:  Can't do replace on working!
Perhaps one of the files already contains 'bar'?
user error (replace patch to ./foo.c couldn't apply.)

and exits with 2. Well, I guess that "user error" part is apt, but
darcs could try a bit harder to detect or prune duplicates in its
argument list.

Luckily it does not trash "pending" like in #231.

Fixed by Tommy's patch