Announce: Flatpak 1.9.1

[Alexander Larsson]

Available here: 
  https://github.com/flatpak/flatpak/releases/tag/1.9.1


$ sha256sum flatpak-1.9.1.tar.xz 
fbac3c49beba82a18bfd0404801f89b9cf71ee713aab76a8d0176f46d967e8ed  flatpak-1.9.1.tar.xz

This is the first unstable release in the series that will lead to
1.10. The main change in this version is a new format for the summary
file used when accessing an OSTree repository on the network. For this
reason we now require OSTree version 2020.8.

The new format should make getting the initial metadata required for
most flatpak operations much faster, and use less network
bandwidth. This will allow repositories to scale to more apps and more
architectures without affecting clients. The old format is still
generated for compatibility with older clients.

The new format also allows repositories to publish named subsets, and
for clients to declare that they only want to see that subset. The
goal here is to allow for example flathub to mark all FOSS apps, and
make it possible for users to use a flathub-foss remote without
flathub having to maintain two duplicated repositories. This is
accessible by passing --subset=SUBSET to the build-commit-from and
build-export commands.

The new repo option `flatpak.summary-arches` controls which architectures
are put in the old format summary. This can be used to avoid newly added
architectures making old clients slower, at the cost of requiring a newer
flatpak client version for the new architecture.

Other major changes
 * There is a new `flatpak pin` command that lets you pin runtimes
   so that they are not considered unused. Also, we now by default pin
   runtimes that are installed explicitly (i.e. not as a dependency of an
   app).
 * During a regular update or uninstall of an app, if the operation
   makes a previously used runtime unused, and the runtime is marked
   as end-of-lifed, then the runtime is automatically uninstalled.
 * During `flatpak update` (i.e. with no specific app given) flatpak
   now automatically adds uninstall operations for end-of-life runtimes
   that are unused.
 * The end-of-life warnings in the flatpak CLI are now better, showing
   more useful details (like version and what apps are using the runtime)
   and less unuseful details.
 * Some changes was made in which dconf paths were considered "similar"
   to the app id, allowing for example `org.gnome.SoundJuicer` to
   migrate from `/org/gnome/sound-juicer`.
 * Flatpak run now implements the new standard for os-release in containers
   (https://www.freedesktop.org/software/systemd/man/os-release.html).
 * There is now a tcsh profile snippet
 * The origin remote for an app is now prioritized over other remotes with
   the same priority when looking for dependencies.
 * We now allow extra-data apply_extra processes to run multiarch code.
 * A new internal representation for ostree ref strings was added which
   is more efficient. This should not affect the behaviour of flatpak
   but the large amounts of changes to use this may have accidentally
   introduced regressions.
 * Some fixes to the in-memory summary cache make it more efficient.
 * --filesystem=/ is now explicitly forbidden as it doesn't work (and never
   did).
 * Flatpak install/update now only prints `(partial)` for an update that
   actually is partial (not just for all locales).
 * Flatpak remote-ls on a file: uri (for example a sideloaded repo) now
   correctly lists the refs in the repo.
 * New library APIS: flatpak_installation_list_pinned_refs,
   flatpak_transaction_set_disable_auto_pin,
   flatpak_transaction_set_include_unused_uninstall_ops,
   flatpak_transaction_operation_get_subpaths,
   flatpak_transaction_operation_get_requires_authentication.
 * flatpak_installation_list_installed_refs_for_update() now returns
   refs that have a end-of-life rebase that it could be updated to.
 * There is a new `ready-pre-auth` signal in FlatpakTransaction allowing
   clients new ways to handling authentication.
 * Fix bug where extension sources were sometimes auto-installed