post-receive-email doesn't list commits after a multi-branch push

Hi all,

I have set up a few git repositories that use the post-receive-email 
script to send an e-mail with the commit logs.

This all works fine if only one branch at a time is updated, but if 
someone does a 'git push' with multiple branches having been updated (in 
my case I commit to one branch and then merge it with another), I get 
one e-mail per changed branch with no commit messages in any of them.

Has anyone else experienced this problem?  Is it a bug in 
post-receive-email or a limitation of the git hook system?

Thanks,
Adam.

(Please CC)