how to get sha1sum of an installed package

[Tom Yates]

in the case of the mailman package, i installed it directly from 
updates-testing using yum, but the package has been deleted from my yum 
cache (by me doing a yum clean).  does anyone know how i can either get 
the sha1sum of the installed package (ie, reconstruct the .rpm file from 
my installed version), or how i can verify that the package i have 
installed matches the .rpm currently in updates-testing?

otherwise, i can't put a sha1sum of the .rpm in my VERIFY report.  any 
bright ideas gratefully received.


-- 

   Tom Yates
   Cambridge, UK.