Previously it was not possible to open a local store when its database is on a read-only filesystem. Obviously a store on a read-only filesystem cannot be modified, but it would still be useful to be able to query it. This change adds a new read-only setting to LocalStore. When set to true, Nix will skip operations that fail when the database is on a read-only filesystem (acquiring big-lock, schema migration, etc), and the store database will be opened in immutable mode. Co-authored-by: Ben Radford <benradf@users.noreply.github.com> Co-authored-by: cidkidnix <cidkidnix@protonmail.com> Co-authored-by: Dylan Green <67574902+cidkidnix@users.noreply.github.com> Co-authored-by: John Ericson <git@JohnEricson.me> Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>