su starts behaving oddly sometimes on F19

[Adam Williamson]

This is a weird bug I've seen 3 or 4 times since upgrading to F19, and
am having trouble pinning down.

Occasionally, after my session has been up for some time, runs of 'su'
start behaving oddly. After I enter the root password, it takes a long
time - longer than the delay that's always happened when you fat-finger
your password, even - before it succeeds. Usually, of course, it's
instant. But when this bug happens, I just get to sit there while it
thinks about it for like 10-15 seconds before I eventually get a root
prompt.

This only applies to my desktop session - but it applies to any terminal
running in the desktop. At least, it applies to gnome-terminal (even if
closed and opened again) and xterm. But if I go to ctrl-alt-f2, login,
and run an 'su', that still returns instantly.

I've tried strace'ing su, but interestingly, I can't get it to work:
running su via strace always seems to result in "Authentication
failure" (which doesn't display this bug; it's only _normally_ slow, the
same slowness that has always been the case when you fail the password).

So I'm kinda stuck, really. Has anyone else seen this? Any bright ideas
for debugging it? Thanks!
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | identi.ca: adamwfedora
http://www.happyassassin.net