[Bug preprocessor/65580] New: Dependency generation has a bug with absent generated include-files in subdirectories

["j at jasper dot es" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65580

            Bug ID: 65580
           Summary: Dependency generation has a bug with absent generated
                    include-files in subdirectories
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: j at jasper dot es

Dependency generation has a bug with absent generated include-files in
subdirectories; steps to reproduce:

spaans@spaans-e6500:/tmp/testcase$ ls
spaans@spaans-e6500:/tmp/testcase$ mkdir a
spaans@spaans-e6500:/tmp/testcase$ cd a
spaans@spaans-e6500:/tmp/testcase/a$ ls
spaans@spaans-e6500:/tmp/testcase/a$ echo '#include "b.h"' > a.h
spaans@spaans-e6500:/tmp/testcase/a$ cd ..
spaans@spaans-e6500:/tmp/testcase$ echo '#include "a/a.h"' >a.c
spaans@spaans-e6500:/tmp/testcase$ gcc -MM -MG a.c
a.o: a.c a/a.h b.h
spaans@spaans-e6500:/tmp/testcase$ touch a/b.h
spaans@spaans-e6500:/tmp/testcase$ gcc -MM -MG a.c
a.o: a.c a/a.h a/b.h

I would have expected the same output for both gcc runs.