Merge branch 'madgraph_pdfsets' into 'master'

Fix issue with access to PDFsets in Madgraph

See merge request !777

Gen/LbMadgraph/src/component/MadgraphProduction.cpp

@@ -81,8 +81,11 @@ StatusCode MadgraphProduction::hardInitialize() {
   if (!m_genGridpack) {
     std::string gridpack = mgdpath + "/gridpacks/" + getenv("CMTCONFIG") + "/"
       + rundir + ".tgz";
-    if (access(gridpack.c_str(), F_OK) != -1)
+    if (access(gridpack.c_str(), F_OK) != -1) {
       system(("tar -xzf" + gridpack).c_str());
+      system(("unlink " + rundir + "/lib/PDFsets").c_str());
+      system(("ln -s $LHAPDFSETSDATA " + rundir + "/lib/PDFsets").c_str());
+    }
     if (access(rundir.c_str(), F_OK) == -1)
       Exception("Gridpack required but not found. To generate a gridpack see "
         "https://gitlab.cern.ch/lhcb-datapkg/Gen/MadgraphData "