bug#5480: threads not expanded when entering a group

[Jose A. Ortega Ruiz]

Using Gnus/5.13 from Emacs/23.1.91 (debian's emacs-snapshot package),
i've been having a problem during the last couple of months: when a
group (either mail or news) has a ticked message and its thread has a
new mail, upon entering the group, i see the new message in the message
buffer, but the thread is not expanded in the summary: actually, i need
to press 'T s' (or call gnus-summary-show-thread) *twice* to finally
expand the thread in the summary. This is not happening in the 23.1
release.

Thanks!
jao