List changed/removed/added files in commit trigger.

I'm trying to create a list of changed, removed and added files during 
post-incoming.

The closest I've come to my goal is an extreme kludge and I'm 
desperately searching for the CorrectWay<TM>

How I currently do it is;

(told you it's a kludge)

while read CSET; do
         bk export -tpatch -h -du $CSET | diffstat -l
done < $BK_CSETLIST | sort -u

which does not always produce the correct output. Any ideas or pointers 
would be helpful.