MDEV-18632: wsrep_is_wsrep_xid: Conditional jump or move depends on uninitialised value

Transaction XID is not initialized before transaction is started.

mysql-test/suite/innodb/r/innodb-rollback.result

+CREATE TABLE t1 (a INT) ENGINE=InnoDB;
+connect  con1,localhost,root,,test;
+ALTER TABLE t1;
+connect  con2,localhost,root,,test;
+SELECT f() FROM t1;
+ERROR 42000: FUNCTION test.f does not exist
+disconnect con2;
+disconnect con1;
+connection default;
+DROP TABLE t1;

mysql-test/suite/innodb/t/innodb-rollback.test

+--source include/have_innodb.inc
+
+#
+# MDEV-18632: wsrep_is_wsrep_xid: Conditional jump or move depends on uninitialised value
+#
+CREATE TABLE t1 (a INT) ENGINE=InnoDB;
+--connect (con1,localhost,root,,test)
+ALTER TABLE t1;
+--connect (con2,localhost,root,,test)
+--error ER_SP_DOES_NOT_EXIST
+SELECT f() FROM t1;
+
+# Cleanup
+--disconnect con2
+--disconnect con1
+--connection default
+DROP TABLE t1;

storage/innobase/handler/ha_innodb.cc

@@ -4712,7 +4712,7 @@ innobase_rollback(
 	trx is being rolled back due to BF abort, clear XID in order
 	to avoid writing it to rollback segment out of order. The XID
 	will be reassigned when the transaction is replayed. */
-	if (wsrep_is_wsrep_xid(trx->xid)) {
+	if (trx->state != TRX_STATE_NOT_STARTED && wsrep_is_wsrep_xid(trx->xid)) {
 		trx->xid->null();
 	}
 #endif /* WITH_WSREP */