Well, at least the culprit is easy to find!
2007-08-16 H.J. Lu <hongjiu.lu@intel.com>
* Makefile.in (REVISION): New.
(REVISION_c): New.
(REVISION_s): New.
(version.o): Also depend on $(REVISION). Add
-DREVISION=$(REVISION_s).
* version.c (version_string): Add REVISION.