bug#13069: 24.3.50; vc-dir: Unify git stashing and bzr shelving

[Stefan Monnier]

> (defun vc-stash (name)
>   "Stash current working tree."
>   (interactive "sName: ")
>   (let* ((vc-fileset (vc-deduce-fileset t)) ;FIXME: Why t? --Stef
>        (backend (car vc-fileset))
>        (files (cadr vc-fileset)))
>     (vc-call-backend backend 'stash name)))

I think we should pass `files' as well.

>   "Take a snapshot of working tree."

Not sure what this means, really.  Especially since the doc of "bzr
shelve --all" is not clear either about what it does (IOW in what way is
it different from "bzr shelve").

> (defun vc-stash-pop ()
>   "Pop newest stash."
>   (interactive)
>   (let* ((vc-fileset (vc-deduce-fileset t)) ;FIXME: Why t? --Stef
>        (backend (car vc-fileset))
>        (files (cadr vc-fileset))
>        (name (vc-stash-name)))
>     (when name
>       (vc-call-backend backend 'stash-pop name))))

I don't think we should impose a stack discipline.  I.e. vc-stash-name
should be replaced by vc-stash-list and then vc-stash-pop should ask the
user to choose among one of the stashes.

Also the stash-pop method should take an extra arg to control whether or
not the stash should be thrown away after application.  And maybe we
shouldn't have a stash-pop at all and instead of stash-apply and
stash-remove, since we'll need stash-remove anyway in order to allow
deleting a stash without applying it.


        Stefan