* Display a warning message when a remote uses a protocol, such as
git://, that git-annex does not support. Silently skipping such a
remote was confusing behavior.
It sets annex-ignore, so the warning is only displayed once.
* Also display a warning message when a remote, without a known uuid,
is located in a directory that does not currently exist, to avoid
silently skipping such a remote.
This is a bit more debatable, since git-annex get will say,
try making repository available. And since it does not set annex-ignore,
the warning will be displayed repeatedly. It's also an extreme edge case,
I don't think I've ever seen it happen in real life.