Avoid insane fiber call

Very rarely case, fiber called `cb` twice.
Add insane fiber call testcase

It just cause `defers` action

Before fix case:
mocha -C test/sync.js

  ․․․․․․․․․․․․․․

  13 passing (158ms)
  1 failing

  1) Control Flow should fiber call just once at raise error:
     Uncaught expected 2683 to deeply equal 1
Fix insane defers call

If throw error in defers call, it cause recall fiber action.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	test/sync.js
Merge pull request #19 from d3m3vilurr/master

Fix insane defers action at raise error