prune --worktrees: fix expire vs worktree existence condition
`git prune --worktrees` was pruning worktrees which were non-existent OR
expired, while it rather should prune those which are orphaned AND
expired, as git-checkout documentation describes. Fix it.
Add test 'not prune proper checkouts', which uses valid but expired
worktree.
Modify test 'not prune recent checkouts' to remove the worktree before
pruning - link in worktrees still must survive. In older form it is
useless because would pass always when the other test passes.
Signed-off-by: Max Kirillov <max@max630.net>
Acked-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>