Bug#423171: possible-missing-colon-in-closes should not check ancient entires

[Thijs Kinkhorst <thijs@debian.org>]

Package: lintian
Version: 1.23.30

Hi,

I got these warnings on checking squirrelmail:

W: squirrelmail: possible-missing-colon-in-closes l436:Closes #143277
W: squirrelmail: possible-missing-colon-in-closes l438:Closes #136612
W: squirrelmail: possible-missing-colon-in-closes l530:Closes #125866

This concerns changelog entries from more than 4 years old. I don't think it's 
right for lintian to be expecting me to change those entries, especially 
because it brings no benefit since that changelog entry will not be processe 
by dak to create close-messages.

I suggest to only check the topmost changelog entry, as some other tests 
already do aswell if I remember correctly.


thanks!
Thijs