Merge branch 'mk/diff-delta-avoid-large-offset'

The delta format used in the packfile cannot reference data at
offset larger than what can be expressed in 4-byte, but the
generator for the data failed to make sure the offset does not
overflow.  This has been corrected.

* mk/diff-delta-avoid-large-offset:
  diff-delta: do not allow delta offset truncation

diff-delta.c

@@ -454,6 +454,9 @@ create_delta(const struct delta_index *index,
 			moff += msize;
 			msize = left;
 
+			if (moff > 0xffffffff)
+				msize = 0;
+
 			if (msize < 4096) {
 				int j;
 				val = 0;