The multi-pack-index (MIDX for short) stores a list of objects
and their offsets into multiple packfiles. It contains:
-- A list of packfile names.
-- A sorted list of object IDs.
-- A list of metadata for the ith object ID including:
- - A value j referring to the jth packfile.
- - An offset within the jth packfile for the object.
-- If large offsets are required, we use another list of large
+* A list of packfile names.
+* A sorted list of object IDs.
+* A list of metadata for the ith object ID including:
+** A value j referring to the jth packfile.
+** An offset within the jth packfile for the object.
+* If large offsets are required, we use another list of large
offsets similar to version 2 pack-indexes.
Thus, we can provide O(log N) lookup time for any number