Confirmed on edgy. thunderbird-locale-en-gb appears to depend on either mozilla-thunderbird OR language-support-en, so it shouldn't force install of the former when the latter is installed. However, it *is* strange that this package is a dependency of language-support-en when Thunderbird isn't part of the basic Ubuntu system.
** Attachment added: "Output of dpkg --status thunderbird-locale-en-gb" http://librarian.launchpad.net/5324017/status.txt -- language-support-en depends on thunderbird-locale-en-gb https://launchpad.net/bugs/64200 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
