Oh dear. Heiko Schlitterman says that he's changed some programs (he doesn't say exactly which) to change the ownership of debian/files and debian/substvars.
This is not a good idea, and doesn't correctly solve the problem
either.
I think that the right fix is to put near the top of dpkg-buildpackage
case `umask` in
*77) echo >&2 \
'dpkg-buildpackage: warning: bad umask will probably break build'
;;
esac
Ian.
