All versions of net-proxy/squid currently in the tree (ie. 2.6.7 and 2.6.9) install auth helpers which require samba to run. The auth helpers in question are: wbinfo_group.pl smb_auth/smb_auth.sh smb_auth.pl Rather than setting an unconditial RDEPEND on samba, it's probably better to make use of the samba USE flag to control installation of the above-mentioned helpers (which isn't guaranteed to be the complete list - only the ones that were obvious to me) .
Fixed in squid-2.6.9-r1. Thanks!