MDEV-7585 Assertion `thd->is_error() || kill_errno || thd->killed ==...

MDEV-7585 Assertion `thd->is_error() || kill_errno || thd->killed == ABORT_QUERY' failed in ha_rows filesort

if we clear the error status (in THD::clear_error())
make sure to clear the thd->killed == KILL_BAD_DATA too,
because it was caused by the error that we're clearing.

mysql-test/r/filesort_bad_i_s-7585.result

+SET sql_mode=STRICT_TRANS_TABLES;
+CREATE TABLE t0 (i INT) ENGINE=MyISAM;
+CREATE VIEW v1 AS SELECT * FROM t0;
+CREATE VIEW v2 AS SELECT * FROM v1;
+DROP VIEW IF EXISTS v1;
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 SELECT TABLE_ROWS FROM information_schema.tables ORDER BY TABLE_ROWS;
+DROP VIEW v2;
+DROP TABLE t1, t0;

mysql-test/t/filesort_bad_i_s-7585.test

+#
+# MDEV-7585 Assertion `thd->is_error() || kill_errno || thd->killed == ABORT_QUERY' failed in ha_rows filesort
+#
+SET sql_mode=STRICT_TRANS_TABLES;
+
+CREATE TABLE t0 (i INT) ENGINE=MyISAM;
+CREATE VIEW v1 AS SELECT * FROM t0;
+CREATE VIEW v2 AS SELECT * FROM v1;
+DROP VIEW IF EXISTS v1;
+
+CREATE TABLE t1 (i INT) ENGINE=MyISAM;
+INSERT INTO t1 SELECT TABLE_ROWS FROM information_schema.tables ORDER BY TABLE_ROWS;
+DROP VIEW v2;
+DROP TABLE t1, t0;

sql/sql_class.h

@@ -2620,6 +2620,8 @@ class THD :public Statement,
     if (stmt_da->is_error())
       stmt_da->reset_diagnostics_area();
     is_slave_error= 0;
+    if (killed == KILL_BAD_DATA)
+      killed= NOT_KILLED; // KILL_BAD_DATA can be reset w/o a mutex
     DBUG_VOID_RETURN;
   }
 #ifndef EMBEDDED_LIBRARY