fixed the contents of RecoBTag/PerformanceDB/python/measure/Pool_btagMistagWinter13.py
Merge pull request #3168 from cms-btv-pog/RecoBTagPerformanceDB-Bugfix_from-CMSSW_5_3_17

Fixed the contents of RecoBTag/PerformanceDB/python/measure/Pool_btagMistagWinter13.py