`charm show` channel output confusing if unpublished

[Jeff Pihach]

When a charm is unpublished the headings for CHANNEL look like the key is CHANNEL and the value is CURRENT not that it's missing data.

I expected there to be an 'unpublished' value there.

charm show cs:~hatch/apple-0
<Fill in summary here>

Name                    apple
Owner                   hatch
Revision                0
Supported Series        xenial
Tags                    misc
Subordinate             false
Promulgated             false
Home page
Bugs url
Read                    hatch
Write                   hatch

CHANNEL                 CURRENT