Check for multiple LHE files is broken

Running an MC generation job with CMSSW_8_0_25 and multiple LHESource input files yields the error "Using an LHESource with more than one input file may not be supported by the CMSSW version used. Consider merging the LHE input files to guarantee complete processing."

It appears there is an attempt to check if the CMSSW version is >= 7_5_X, but the implementation warns on 8_0_25
https://github.com/dmwm/CRABClient/blob/master/src/python/CRABClient/JobType/PrivateMC.py#L33