yum upgrade creates /var/run/nologin

[Andrew Lutomirski]

This has happened twice now.  I run 'yum upgrade' and, all of a
sudden, /var/run/nologin exists.  It contains a message telling me
that my system is still booting.  This is, of course, a lie -- the
system has been up for quite a while, *and I'm logged in with the
screen locked*.

This is rather impolite.  /var/run/nologin isn't owned by any package,
so I have no clue where to file the bug.

--Andy