Requirement for Boto 0.9d is out of date

In the duplicity readme file there is a documented requirement for Boto 0.9d or later. This appears to be out of date now. I just upgraded duplicity from 0.4.10 to 0.5.20 to fix a problem with gpg 'invalid packet (ctb=14)'. Previously this was working fine with boto 1.1c installed. After the upgrading to duplicity 0.5.20 I was getting an error from duplicity that said

It seems we previously failed to detect support for calling formats in the boto library, yet the support is there. This is almost certainly a duplicity bug.

I tried specifying --s3-use-new-style --s3-european-buckets on my duplicity command line to see if this would bypass the error but it just gave me something slightly different (sorry, this one has scrolled off my scrollback buffer and I no longer remember what it was). Upgrading duplicity was the only change made at this point.

Upgraded boto from 1.1c to 1.8d and now everything is working correctly again.

Duplicity version: 0.5.20
Python 2.4.3
Host o/s: Centos 5.3
File system: ext3
Backup to s3+http on a european bucket