ITS#8819 can't use fakepage mp_ptrs directly

libraries/liblmdb/mdb.c

@@ -6799,8 +6799,9 @@ prep_subDB:
 				} else {
 					memcpy((char *)mp + mp->mp_upper + PAGEBASE, (char *)fp + fp->mp_upper + PAGEBASE,
 						olddata.mv_size - fp->mp_upper - PAGEBASE);
+					memcpy((char *)(&mp->mp_ptrs), (char *)(&fp->mp_ptrs), NUMKEYS(fp) * sizeof(mp->mp_ptrs[0]));
 					for (i=0; i<NUMKEYS(fp); i++)
-						mp->mp_ptrs[i] = fp->mp_ptrs[i] + offset;
+						mp->mp_ptrs[i] += offset;
 				}
 			}