partially revert commit be4081ba0
partially revert commit be4081ba0

* Fiber is improved to be exception-safe across threads, the fix is not
  needed anymore
* remove the fix but keep the unit test

Change-Id: I6e7a08b3abe70d539599d9517ae982602fbecfb4
Signed-off-by: Kevin Cai <c4f49ef5a44534d46de426dda18a118a2ca4debf@mozy.com>
Reviewed-on: https://gerrit.dechocorp.com/36079
Reviewed-by: Jenkins <49695b0f9c673fd73dab0ff3f84b5ced9302cc6a@mozy.com>
Reviewed-by: Andrew Skowronski <c8c00996ab6ab4cf2bc95b6ba564113014e37b00@vmware.com>

mtanski/mordor,mozy/mordor,adfin/mordor,mozy/mordor,mtanski/mordor,adfin/mordor,mtanski/mordor,adfin/mordor,mozy/mordor