bugfix: TABLE::mark_columns_used_by_index

Do *not* modify write_set.
keyread only affects what columns are *read*, UPDATE statement can
*write* into columns that aren't part of the keyread.

sql/table.cc

@@ -6088,7 +6088,7 @@ void TABLE::mark_columns_used_by_index(uint index)
   file->ha_start_keyread();
   bitmap_clear_all(bitmap);
   mark_columns_used_by_index_no_reset(index, bitmap);
-  column_bitmaps_set(bitmap, bitmap);
+  column_bitmaps_set(bitmap);
   DBUG_VOID_RETURN;
 }
 

sql/table.h

@@ -1321,6 +1321,12 @@ public:
   void mark_columns_used_by_check_constraints(void);
   void mark_check_constraint_columns_for_read(void);
   int verify_constraints(bool ignore_failure);
+  inline void column_bitmaps_set(MY_BITMAP *read_set_arg)
+  {
+    read_set= read_set_arg;
+    if (file)
+      file->column_bitmaps_signal();
+  }
   inline void column_bitmaps_set(MY_BITMAP *read_set_arg,
                                  MY_BITMAP *write_set_arg)
   {