protection against corrupt O2DPG repository during topology generation

DATA/tools/epn/gen_topo_o2dpg.sh

@@ -82,14 +82,26 @@ while true; do
         break
       fi
     fi
-    if [[ ! -d O2DPG ]]; then git clone https://github.com/AliceO2Group/O2DPG.git 1>&2 || { echo O2DPG checkout failed 1>&2; exit 1; }; fi
-    cd O2DPG
-    git checkout $GEN_TOPO_SOURCE &> /dev/null
-    if [[ $? != 0 ]]; then
-      git fetch --tags origin 1>&2 || { echo Repository update failed 1>&2; exit 1; }
-      git checkout $GEN_TOPO_SOURCE &> /dev/null || { echo commit does not exist 1>&2; exit 1; }
-    fi
-    git reset --hard $GEN_TOPO_SOURCE &> /dev/null  || { echo git reset error 1>&2; exit 1; }
+    CHECKOUTATTEMPT=1
+    while true; do    
+      if [[ ! -d O2DPG ]]; then git clone https://github.com/AliceO2Group/O2DPG.git 1>&2 || { echo O2DPG checkout failed 1>&2; exit 1; }; fi
+      cd O2DPG
+      git checkout $GEN_TOPO_SOURCE &> /dev/null
+      if [[ $? != 0 ]]; then
+        git fetch --tags origin 1>&2 || { echo Repository update failed 1>&2; exit 1; }
+        git checkout $GEN_TOPO_SOURCE &> /dev/null || { echo commit does not exist 1>&2; exit 1; }
+      fi
+      git reset --hard $GEN_TOPO_SOURCE &> /dev/null
+      if [ $? -eq 0 ]; then
+        break
+      else
+        [[ $CHECKOUTATTEMPT -eq 2 ]] && { echo git reset error 1>&2; exit 1; }
+        echo "First attempt to checkout O2DPG failed. Cleaning up and trying a second time" 1>&2
+        CHECKOUTATTEMPT=2
+        cd $GEN_TOPO_WORKDIR || { echo Cannot enter work dir 1>&2; exit 1; }
+        rm -rf O2DPG
+      fi
+    done
     rm -f DATA/core_dump_*
     # At a tag, or a detached non-dirty commit, but not on a branch
     if ! git describe --exact-match --tags HEAD &> /dev/null && ( git symbolic-ref -q HEAD &> /dev/null || ! git diff-index --quiet HEAD &> /dev/null ); then