Merge branch 'bc/object-id' into base
refs: don't dereference on rename
refname_is_safe(): insist that the refname alre...
refname_is_safe(): don't allow the empty string
safe_create_leading_directories(): improve docs...
commit_ref_update(): remove the flags parameter
lock_ref_sha1_basic(): only handle REF_NODEREF ...
refs: resolve symbolic refs first