shelve: also create class representing whole directory of shelves It's a little annoying to have to create and pass in a vfs into `listshelves()`. This patch attempts to start addressing that by creating a class that represents a directory containing shelves (the directory can be either `.hg/shelved/` or `.hg/shelve-backup/`). Differential Revision: https://phab.mercurial-scm.org/D9743

shelve: add a method for deleting shelf to new shelf class This is not necessary for my future changes, but it's more consistent to encapsulate the knowledge of the various files in the `Shelf` class. Differential Revision: https://phab.mercurial-scm.org/D9742

shelve: inline ".patch" constant now that it's only used in the Shelf class Differential Revision: https://phab.mercurial-scm.org/D9741

shelve: use listshelves() in cleanupoldbackups() With this patch, there are no more assumptions outside the `Shelf` class about which files (`.patch`, `.hg`, `.shelve`) make up a shelf. As such, this finishes the preparations for making phase-based shelve (perhaps optionally) not write the `.patch` and `.hg` files. Differential Revision: https://phab.mercurial-scm.org/D9740

shelve: make listshelves() list shelves in a given vfs Differential Revision: https://phab.mercurial-scm.org/D9739

shelve: replace repo instance in Shelf class by vfs instance I'd like to be able to teach the `Shelf` class to read shelves from `.hg/shelve-backup/` in addition to `.hg/shelved/`. That means that we'll have to pass in a vfs instead of the repo, so this patch does that preparation. Differential Revision: https://phab.mercurial-scm.org/D9738

shelve: use listdir() instead of readdir() when we don't need stat information Differential Revision: https://phab.mercurial-scm.org/D9737

shelve: don't crash on file with unexpected extension in .hg/shelved/ We assumed that the files in the `.hg/shelved/` directory have an extension. That's a valid assumption except that users may put garbage in the directory. This patch fixes the crash by simply not assuming that the result of splittin a string at '.' yields an extension. We don't use the extension since the previous patch anyway. Differential Revision: https://phab.mercurial-scm.org/D9720

shelve: don't include invalid shelves in `hg shelve --list` Before this patch, if a shelved change is missing its `.hg` file, we still list it in `hg shelve --list`, but then `hg unshelve` crashes. This patch makes it so we only list valid shelved changes. This patch means that users who do `touch .hg/shelve/buy-milk.patch` as a form of TODO list will no longer see their TODO items in `hg shelve --list`. Differential Revision: https://phab.mercurial-scm.org/D9719

shelve: extract some repeated creation of shelf instances to variables This just looks cleaner to me; I'd be surprised if there's any measurable performance improvement. Differential Revision: https://phab.mercurial-scm.org/D9714

shelve: teach new shelf class to check if .shelve file exists This removes the only remaining use for `shelvedfile`, so the class now goes away. Differential Revision: https://phab.mercurial-scm.org/D9713

shelve: move method for creating backup to new shelf class Differential Revision: https://phab.mercurial-scm.org/D9712

shelve: make gennames() helper generate relative backup paths When I saw `gennames()`, I thought it was meant to take a relative filename as argument. Maybe it was or maybe it wasn't, but it seems simpler to pass it a relative path anyway, so that's what this patch does. That also makes the call to backupvfs.exists() more natural (I expect a relative path to be passed there too). Differential Revision: https://phab.mercurial-scm.org/D9711

shelve: use listshelves() in cleanup function The point of this patch is to make it so all the callers of `shelvedfile.movetobackup()` look the same, so I can move it over to the new `Shelf` class next. Differential Revision: https://phab.mercurial-scm.org/D9710

shelve: inline shelvedfile.filename() since there are no callers outside class Differential Revision: https://phab.mercurial-scm.org/D9709