with valid names, the ***/---names were taken first.
this broke eg:
Index: foo/Makefile
==========
RCS <blah>
Retrieving <blah>
diff <blah>
*** Makefile <blah>
--- Makefile <blah>
By trying to patch the Makefile in the _curent_ directory, rather than
the one in the foo/ directory.
in the diff. This makes it so that diffs containing files in different
subdirectories that have the same name not patch the same file. For example
a diff with patches to Makefile, des/Makefile, usr.bin/Makefile would attempt
to patch Makefile three times.