@@debug_dbug and @@debug_sync accept null bytes

--source include/have_debug.inc

SET @saved_dbug= @@GLOBAL.debug_dbug;

SET       @@GLOBAL.debug_dbug= 'd,A\0C';

SELECT    @@GLOBAL.debug_dbug , #=> Expected: d,A␀C. Actual: d,A

  LENGTHB(@@GLOBAL.debug_dbug); #=> Expected: 5. Actual: 3

SET @@GLOBAL.debug_dbug= @saved_dbug;

--source include/have_debug_sync.inc

SET       @@SESSION.debug_sync= 'now SIGNAL A\0C';

SELECT    @@SESSION.debug_sync , #=> Expected: … A␀C. Actual: … A

  LENGTHB(@@SESSION.debug_sync); #=> Expected: 27. Actual: 24

SET @@SESSION.debug_sync= RESET;