buildworld fails with "Zero byte read from file, skipping rest of line"

Hi,

I have a FreeBSD -CURRENT in Virtualbox (running on Linux).  I have been
unable to buildworld for a while.

I suspect this is not a problem with the source because I didn't see any
report so far, whereas I've been experiencing this for a month or more.
Thus I naturally suspected it was a binary problem, so I've upgraded
to the latest snapshot, but the problem still exists.

  ===> gnu/usr.bin/groff/src/libs/libgroff (all)
  make[6]: "/usr/obj/usr/src.svn/tmp/usr/src.svn/gnu/usr.bin/groff/src/libs/libgroff/.depend" line 3: warning: Zero byte read from file, skipping rest of line.
  make[6]: "/usr/obj/usr/src.svn/tmp/usr/src.svn/gnu/usr.bin/groff/src/libs/libgroff/.depend" line 3: Need an operator
  make[6]: "/usr/obj/usr/src.svn/tmp/usr/src.svn/gnu/usr.bin/groff/src/libs/libgroff/.depend" line 4: Need an operator
  make[6]: Fatal errors encountered -- cannot continue
  make[6]: stopped in /usr/src.svn/gnu/usr.bin/groff/src/libs/libgroff
  *** [all] Error code 1

Typscript available here:
http://people.freebsd.org/~jlh/typescript.buildworld.txt

Any ideas?

Cheers,
-- 
Jeremie Le Hen

Scientists say the world is made up of Protons, Neutrons and Electrons.
They forgot to mention Morons.