duplicity, backup to ftp and specifying a user name

[Darin Strait <darin.strait@ashdar-partners.com>]

I am attempting to use duplicity to store backups at a remote site
(host.com).

The ftp user name is someuser@host.com. I do not have control over this
name. Simply using someuser will not work.

If I tell duplicity to use:

ftp://someuser@host.com@host.com

duplicity seems to not be able to parse the hostname properly and can't
even connect to the remote server. If I try:

ftp://someuser@host.com

I get an error about failed security:

duplicity.backends.BackendException: (-2, 'Name or service not known')

I don't see any way to specify a ftp user name through an environment
variable.

Does anyone have a way around this, short of my storing the backups
locally and using ncftp to copy them to the remote site?