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

"git clone" has been prepared to allow cloning a repository with non-default hash function into a repository that uses the reftable backend. * 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