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

[ferencek]

Same as #3164. Bugfix for the problem reported in https://hypernews.cern.ch/HyperNews/CMS/get/btag/1070.html. The bug originally sneaked in with #1365.

Note that this PR has zero impact on the standard reconstruction.

[cmsbuild]

A new Pull Request was created by @ferencek (Dinko Ferencek) for CMSSW_6_2_X_SLHC.

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

It involves the following packages:

RecoBTag/PerformanceDB

@nclopezo, @cmsbuild, @anton-a, @thspeer, @slava77, @Degano can you please review it and eventually sign? Thanks.
@pvmulder this is something you requested to watch as well.
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@andersonjacob, @mark-grimes you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[mark-grimes]

merge

Details under #3176