I can confirm this bug.. I kept running into it today and it was driving me nuts... I narrowed the trigger down to a custom script I wrote... I can easily replicate the problem with the following two commands:
sudo ifdown lo sudo shutdown -h 0 Causes portmap to freeze the system on shutdown for at least a full minute on my system.. Since my script was triggered by a low battery event, the system runs out of battery before it shuts down because it sits around for a minute waiting for portmap to end. The actual command I used was sudo ifdown -a but just taking out the lo is enough to cause portmap to hang up.. -David

