The pam_wheel.so module no longer works correctly (for su) in edge.  The
following /etc/pam.d/su config should allow users to su to root without
a passwd if they are part of the wheel group.  On a current SL-OSS-edge
system, it is still prompting for a passwd.

#%PAM-1.0
auth     sufficient     pam_wheel.so trust
auth     sufficient     pam_rootok.so
auth     include        common-auth
account  include        common-account
password include        common-password
session  include        common-session
session  optional       pam_xauth.so

Adding the "debug" option to the pam_wheel.so line doesn't add much:

Nov 11 08:25:10 fairseas su: pam_wheel(su:auth): who is running me ?!
Nov 11 08:25:13 fairseas su: (to root) gedwards on /dev/pts/1