Merge branch 'ps/clone-into-reftable-repository' into ps/refstorage-extension

* ps/clone-into-reftable-repository: builtin/clone: create the refdb with the correct object format builtin/clone: skip reading HEAD when retrieving remote builtin/clone: set up sparse checkout later builtin/clone: fix bundle URIs with mismatching object formats remote-curl: rediscover repository when fetching refs setup: allow skipping creation of the refdb setup: extract function to create the refdb