Overriding the cache to avoid high failure rates seen in production when reading pileup datasets via xrootd.
Merge pull request #2649 from ktf/Xrootd-failure-caching-bockelfix

Overriding the cache to avoid high failure rates seen in production when...
Merge remote branch 'origin/CMSSW_7_0_X' into CMSSW_7_0_X