I found that problem while trying to compile samba twice in the same
directory while fight^W preparing Debian packages.
Apparently bin/cifs.upcall is not cleaned out by the clean target
while it was in 3.2.* series.
My wild guess is that this pertains to source/Makefile.in:
SBIN_PROGS = bin/smbd@EXEEXT@ bin/nmbd@EXEEXT@ @SWAT_SBIN_TARGETS@ @EXTRA_SBIN_PROGS@ @CIFSUPCALL_PROGS@
ROOT_SBIN_PROGS = @CIFSMOUNT_PROGS@
SBIN_PROGS = bin/smbd@EXEEXT@ bin/nmbd@EXEEXT@ @SWAT_SBIN_TARGETS@ @EXTRA_SBIN_PROGS@
Cannot reproduce in the current v3-3-test branch, so it seems to be fixed meanwhile.
Closing out bug report.
Please re-open if it's still an issue.
Thanks for reporting!