I apologize for deliberately filing a duplicate bug, however this needs to be addressed urgently: using the currently available ebuild will break PAM integration on systems that rely on the PAM functionality that's present in su and login. Please see bug #81844, which already has a fix for this issue (adds login and su to the rename list).
just so you know, they don't actually replace those executables. shadow and pam and coreutils install the originals in /bin. heimdal installs into /usr/bin
*** This bug has been marked as a duplicate of 81844 ***