Code review comment for lp://staging/~jimbaker/pyjuju/scp-command

LGTM, +1. Some minors

[0] as noted by william there is significant duplication between
ssh/scp commands that should be remedied prior to merge.

[1] please clean up the default help output, ie. the output on juju -h
should be one line.

[2]
    """XXX"""

NSFW ? ;-)

[3] actually this applies to both the scp and and ssh branches, but
i'd drop the 'passthrough' in the help output, it causes it to wrap on
the cli. we should probably METAVAR environment to ENV to try and get
this under 80.

[4] The detailed help should note the path prefix when using a unit for an address, else the implemented behavior is likely to be confusing.