including files in a symlink directory when backing up with duplicity

Duplicity doesn't follow symlinks by design. This is because if you tried to restore from that, it'd restore the actual files, and not a symlink! It's not a very good backup if it doesn't restore things to the way they were before. It should, however, be able to backup the symlink itself, and then you should make a backup of the symlink'd data separately.

Starting with Duplicity 0.8, the --copy-links flag should do exactly what you want:

This allows us to dereference and include what symlinks point to in our backup.

I named the argument --copy-links. This is the name rsync gives to a similar flag.