Currently, if flatpak_installed_ref_get_latest_commit() returns NULL
(which means the ref doesn't exist in the local repo) we assume any
remote commit could be an update in
flatpak_installation_list_installed_refs_for_update() when a collection
ID is not configured on the remote. When a collection ID is configured,
if get_latest_commit() returns NULL it causes a crash in
ostree_repo_load_commit(). So this commit prevents the crash and makes
the behavior in the post-collection-id world consistent with the
behavior in the pre-collection-id world.
It's difficult to write a test for this that's not contrived, without
knowing what circumstances led to the disappearance of the ref from the
repo.
Fixes https://github.com/flatpak/flatpak/issues/2216Closes: #2229
Approved by: alexlarsson
6b4402b60e