This works, but needs more testing and work on cases like encrypted repos,
enabling existing repositories, etc.
This commit was sponsored by Shaun Westmacott.
I've seen rss feeds that have no permalinks, only guids (which are
sometimes in the form of permalinks, argh/sigh).
I had previously avoided trusting guids to be globally unique, because my
survey of rss feeds that I subscribe to shows a lot of pretty bad
"guids" like "2 at http://serialpodcast.org" or even worse "oth20150401-hq".
Worry was that two podcasts that are generating guids so badly, that
there's no guarantee they're actually globally unique.
But, I'm seeing too many url changes that result in redundant files, so
let's try this. If feeds are so broken that guids overlap, they could just
as well incorrectly call them permalinks too.
Work around https://github.com/pcapriotti/optparse-applicative/issues/146
by not using action "file" and instead passing -o bashdefault -o default
to complete. This way, when optparse fails to complete a filename, bash
will fall back to regular filename completion.
Unfortunately, optparse-applicative does not provide a way to control the
options passed to complete, so I had to modify its generated completion script.
Note that for "git annex" command completion, git's completion script already
used -o bashdefault -o default, so that works too.
