pam_ck_connector causes su to emit spurious X11 warning

[Owen Dunn]

Ubuntu 14.04
libpam-ck-connector 0.4.5-3.1ubuntu2

When I su I get an error message:

osd1000@wocbox:~$ su
Password:
X11 connection rejected because of wrong authentication.
root@wocbox:/home/osd1000#

This comes from the pam_ck_connector.so PAM module in common-session.
I'm using pam_xauth.so elsewhere in the session stack so once I have su-ed,
X11 apps work normally. (My /etc/pam.d/common-session is attached.)

Since the pam_ck_connector manpage says "only local login managers
such as login(1) should use this" I don't think it should be in the session
stack for su.

Owen