Bug #28355 Execution of events may be delayed - leave gap before checking

Description:
Observed during the release build of 5.1.18,
only once,
on Linux (x86_64) using icc in the PS test run,
but I assume this is pure chance.

-------------------------------------------------------
*** r/rpl_events.result
--- r/rpl_events.reject
***************
*** 24,37
  SELECT * FROM t1 WHERE c = 'from justonce' OR c = 'manually' ORDER BY id;
  id    c       ts
  1     manually        TIMESTAMP
! 2     from justonce   TIMESTAMP
! affected rows: 2
  "in the slave"
  SELECT * FROM t1 WHERE c = 'from justonce' OR c = 'manually' ORDER BY id;
  id    c       ts
  1     manually        TIMESTAMP
! 2     from justonce   TIMESTAMP
! affected rows: 2
  SELECT db, name, status, originator FROM mysql.event WHERE db = 'test' AND name = 'justonce';
  db    name    status  originator
  DROP EVENT IF EXISTS test.slave_once;
--- 24,35
  SELECT * FROM t1 WHERE c = 'from justonce' OR c = 'manually' ORDER BY id;
  id    c       ts
  1     manually        TIMESTAMP
! affected rows: 1
  "in the slave"
  SELECT * FROM t1 WHERE c = 'from justonce' OR c = 'manually' ORDER BY id;
  id    c       ts
  1     manually        TIMESTAMP
! affected rows: 1
  SELECT db, name, status, originator FROM mysql.event WHERE db = 'test' AND name = 'justonce';
  db    name    status  originator
  DROP EVENT IF EXISTS test.slave_once;
-------------------------------------------------------

From looking at the test, I assume that the event (scheduled at "now + 2 seconds") simply was not executed within 3 seconds due to some scheduling (or machine load) effect.

How to repeat:
Run the test sufficiently often.

Suggested fix:
Increase the difference between event delay (2 seconds) and result check (3 seconds).

Duplicate of BUG#28991.