patch: fix typo in variable name

mercurial/patch.py

@@ -1378,7 +1378,7 b' def _externalpatch(ui, repo, patcher, pa'
             cwd = repo.getcwd()
             if cwd:
                 cfiles = [util.pathto(repo.root, cwd, f)
-                          for f in cfile]
+                          for f in cfiles]
             scmutil.addremove(repo, cfiles, similarity=similarity)
     code = fp.close()
     if code: