Comment 2 for bug 1094990

Concur with above: mdm may be the culprit

Doing some trial and error, logging in with the graphical interface will ignore umask settings in the following files:

/etc/pam.d/login
/etc/pam.d/mdm
/etc/pam.d/common-session
/etc/login.defs

When logging in through the terminal, umask and usergroups_enab settings work as expected