Note: This is an as of yet untested solution. I applied it remotely and haven’t had a chance to verify that it actually works. Also, these aren’t the exact steps I took but a sketch. Please try to understand what you’re doing with each command before executing it.
sudo checkgmail -update # answer yes to update
wget 'http://ur1.ca/5284y' -O /tmp/checkgmail.patch # 
sudo patch `which checkgmail` /tmp/checkgmail.patch
I based this on the thread with the patch over at SourceForge and some other thread on Ubuntu Forums (I think), which I don’t have the link to right now.
 The shortened url points to http://sourceforge.net/tracker/download.php?group_id=137480&atid=738663&file_id=423104&aid=3406322 (where the patch lies).