Add more assertions.

dulwich/object_store.py

@@ -476,6 +476,7 @@ class DiskObjectStore(PackBasedObjectStore):
 
         # Complete the pack.
         for ext_sha in indexer.ext_refs():
+            assert len(ext_sha) == 20
             type_num, data = self.get_raw(ext_sha)
             offset = f.tell()
             crc32 = write_pack_object(f, type_num, data, sha=new_sha)

dulwich/tests/utils.py

@@ -230,6 +230,7 @@ def build_pack(f, objects_spec, store=None):
     expected = []
     for i in xrange(num_objects):
         type_num, data, sha = full_objects[i]
+        assert len(sha) == 20
         expected.append((offsets[i], type_num, data, sha, crc32s[i]))
 
     sf.write_sha()