Container fails to connect to scp or sftp using default backend

[aenima]

It seems like some required module for the default scp / sftp backend used by duplicity is missing in the container. When I try to connect to some scp scheme url, I get the following:

user@host:~# docker run --rm wernight/duplicity duplicity /root scp://192.168.0.1/test 
BackendException: Could not initialize backend: No module named paramiko

In this example, a scp url is used, but the error is the same for sftp urls. Also, the host doesn't have to be available for an actual connection, because the docker image is obviously missing the required package.

[aenima]

After merging the bugfix, this should be working now. Closing