branches/zip: row_undo_mod_del_mark_or_remove_sec_low(): Complain if

the secondary index entry cannot be found, and this is not an incomplete
transaction that is being rolled back in crash recovery.  The source code
comments were suggested by Heikki.

row/row0umod.c

@@ -312,7 +312,30 @@ row_undo_mod_del_mark_or_remove_sec_low(
 	btr_cur = btr_pcur_get_btr_cur(&pcur);
 
 	if (!found) {
-		/* Not found */
+		/* In crash recovery, the secondary index record may
+		be missing if the UPDATE did not have time to insert
+		the secondary index records before the crash.  When we
+		are undoing that UPDATE in crash recovery, the record
+		may be missing.  In normal processing, the record
+		SHOULD exist. */
+		trx_t*	trx = thr_get_trx(thr);
+
+		if (!trx_is_recv(trx)) {
+			fputs("InnoDB: error in sec index entry del undo in\n"
+			      "InnoDB: ", stderr);
+			dict_index_name_print(stderr, trx, index);
+			fputs("\n"
+			      "InnoDB: tuple ", stderr);
+			dtuple_print(stderr, entry);
+			fputs("\n"
+			      "InnoDB: record ", stderr);
+			rec_print(stderr, btr_pcur_get_rec(&pcur), index);
+			putc('\n', stderr);
+			trx_print(stderr, trx, 0);
+			fputs("\n"
+			      "InnoDB: Submit a detailed bug report"
+			      " to http://bugs.mysql.com\n", stderr);
+		}
 
 		btr_pcur_close(&pcur);
 		mtr_commit(&mtr);