CMSSW_10_2_26

Changes since CMSSW_10_2_25:

compare to previous

CMSDIST Changes between Tags REL/CMSSW_10_2_25/slc6_amd64_gcc700 and REL/CMSSW_10_2_26/slc6_amd64_gcc700:

compare to previous

1. 6680 from @SiewYan: [10_2_X] upgrade sherpa 2.2.10 to 2.2.11 created: 2021-02-25 16:15:14 merged: 2021-02-26 12:23:12

2. 6474 from @Dominic-Stafford: Upgrade Herwig to v7.2.1, and add patch to fix crash when reading lhe created: 2020-12-01 13:54:02 merged: 2020-12-24 15:31:51