Cacti 0.8.7b SNMPv3 Password Error

Thanks to Richard Bronsky on the www.cacti.net forums:

1. For installations on Ubuntu 8.04, go here:
/usr/share/cacti/site

2. Pre-work
sudo apt-get install curl patch

3. THIS IS IMPORTANT. Verify the validity of the URI like this:
sudo curl -L http://forums.cacti.net/download.php?id=14681

4. If it looks like a safe patch, then apply it directly from that URI via curl:
sudo curl -L http://forums.cacti.net/download.php?id=14681|sudo patch -p1 -N