newvers.sh: can't find dirname?

   This is the second time I've seen this (I forgot why I fixed it the
first time, reverted the local change, and ran into the change the
second time):

===> include (install)
creating osreldate.h from newvers.sh
NEWVERS PATH: /usr/obj/usr/src/tmp/legacy/usr/sbin:/usr/obj/usr/src/tmp/legacy/usr/bin:/usr/obj/usr/src/tmp/legacy/usr/games:/usr/obj/usr/src/tmp/usr/sbin:/usr/obj/usr/src/tmp/usr/bin:/usr/obj/usr/src/tmp/usr/games:/tmp/install.Nuxzcgf9
/usr/src/include/../sys/conf/newvers.sh: dirname: not found

...

# dirname
usage: dirname string [...]

   I hacked around this by adding dirname to $PATH in newvers.sh (if
you look at the above $PATH printed out, it doesn't contain /bin and
/usr/bin -- both which are required to run the above commands), but I
was wondering if anyone else has run into this issue before, and
whether or not a better solution was in the works (maybe).
Thanks,
-Garrett