records tip-of-the-tree commit objects of branches copied
from a remote repository.
+refs/replace/`<obj-sha1>`::
+ records the SHA1 of the object that replaces `<obj-sha1>`.
+ This is similar to info/grafts and is internally used and
+ maintained by linkgit:git-replace[1]. Such refs can be exchanged
+ between repositories while grafts are not.
+
packed-refs::
records the same information as refs/heads/, refs/tags/,
and friends record in a more efficient way. See