exclude pytest 2.8.0
exclude pytest 2.8.0

 py26 test failed with pytest 2.8.0

Change-Id: I9788b066f25991574402d22e917caf48ba2de9e5
Closes-Bug: #1497933

eayunstack/fuel-library,huntxu/fuel-library,stackforge/fuel-library,ddepaoli3/fuel-library-dev,stackforge/fuel-library,huntxu/fuel-library,ddepaoli3/fuel-library-dev,ddepaoli3/fuel-library-dev,xarses/fuel-library,huntxu/fuel-library,huntxu/fuel-library,eayunstack/fuel-library,ddepaoli3/fuel-library-dev,eayunstack/fuel-library,eayunstack/fuel-library,xarses/fuel-library,xarses/fuel-library,ddepaoli3/fuel-library-dev,stackforge/fuel-library,stackforge/fuel-library,eayunstack/fuel-library,huntxu/fuel-library,xarses/fuel-library