rename --after: do not unlink source file (issue910)

"rename --after a.txt A.txt" on case mangling systems (e.g. Windows)
erroneously deleted A.txt (even if modified).

mercurial/cmdutil.py

@@ -395,7 +395,7 b' def copy(ui, repo, pats, opts, rename=Fa'
                 repo.copy(origsrc, abstarget)
 
         if rename and not dryrun:
-            repo.remove([abssrc], True)
+            repo.remove([abssrc], not after)
 
     # pat: ossep
     # dest ossep