Added a convenience Utility.LockFile that is not a windows/posix
portability shim, but still manages to cut down on the boilerplate around
locking.
This commit was sponsored by Johan Herland.
This was a bug, but it was only used for ssh locks and by the hook special
remote locking. At least in the case of ssh locks, the lock files happened
to already exist before this tried to use them, so the bug didn't cause
anything to break.
(With the exception of daemon pid locking.)
This fixes at part of #758630. I reproduced the assistant locking eg, a
removable drive's annex journal lock file and forking a long-running
git-cat-file process that inherited that lock.
This did not affect Windows.
Considered doing a portable Utility.LockFile layer, but git-annex uses
posix locks in several special ways that have no direct Windows equivilant,
and it seems like it would mostly be a complication.
This commit was sponsored by Protonet.
Removed old extensible-exceptions, only needed for very old ghc.
Made webdav use Utility.Exception, to work after some changes in DAV's
exception handling.
Removed Annex.Exception. Mostly this was trivial, but note that
tryAnnex is replaced with tryNonAsync and catchAnnex replaced with
catchNonAsync. In theory that could be a behavior change, since the former
caught all exceptions, and the latter don't catch async exceptions.
However, in practice, nothing in the Annex monad uses async exceptions.
Grepping for throwTo and killThread only find stuff in the assistant,
which does not seem related.
Command.Add.undo is changed to accept a SomeException, and things
that use it for rollback now catch non-async exceptions, rather than
only IOExceptions.
