While doing some repair/maintenance works on a Gentoo system I administer, I noticed the files in /var/cache/revdep-rebuild all have their executable bit set. Looking through /usr/bin/revdep-rebuild, I found a 'chmod 700 "$file"' on line 627, which should probably be 'chmod 600 "$file"'. Also, I couldn't find any explicit setting of umask in the script, so that should probably be added somewhere in the initialisation?
Fix is in git: http://git.overlays.gentoo.org/gitweb/?p=proj/gentoolkit.git;a=commit;h=6d3eb84a5739faf2c4dcb6030791fdd7491ce570
Released in gentoolkit-0.3.0.2