Merge branch 'ps/submodule-ref-format'

Support to specify ref backend for submodules has been enhanced. * ps/submodule-ref-format: object: fix leaking packfiles when closing object store submodule: fix leaking seen submodule names submodule: fix leaking fetch tasks builtin/submodule: allow "add" to use different ref storage format refs: fix ref storage format for submodule ref stores builtin/clone: propagate ref storage format to submodules builtin/submodule: allow cloning with different ref storage format git-submodule.sh: break overly long command lines