This is groundwork for making special remotes like borg be skipped by
sync when on an offline drive.
Added AVAILABILITY UNAVAILABLE reponse and the UNAVAILABLERESPONSE extension
to the external special remote protocol. The extension is needed because
old git-annex, if it sees that response, will display a warning
message. (It does continue as if the remote is globally available, which
is acceptable, and the warning is only displayed at initremote due to
remote.name.annex-availability caching, but still it seemed best to make
this a protocol extension.)
The remote.name.annex-availability git config is no longer used any
more, and is documented as such. It was only used by external special
remotes to cache the availability, to avoid needing to start the
external process every time. Now that availability is queried as an
Annex action, the external is only started by sync (and the assistant),
when they actually check availability.
Sponsored-by: Nicholas Golder-Manning on Patreon
Only display warning when git-annex sync (without --content or
--no-content) is used with repositories that have preferred content
configured.
Sponsored-by: Leon Schuermann on Patreon
I considered a more wide-ranging config option to make other commands
also show dead repositories. But it would be difficult to implement that
because Remote.keyLocations is used to get locations, filtering out dead
repos, and commands like get then try to use those locations. So a config
setting would make dead repos sometimes be acted on by commands.
Sponsored-by: unqueued on Patreon
Using == and != proved too hard to read, so went with [TRUE] and [FALSE]
after the term. I would kind of liked to have used emojis for a green
check and red X, but probably that is too fancy to be a good idea.
Make --explain output be inside [ ] with whitespace around them, to
avoid it ending with eg "[FALSE]]" and to make it easier to visually
find the start of it.
Sponsored-by: Dartmouth College's DANDI project
