Bug fix for reproducible build (#8061)

Author: liushilongbuaa

src/sonic-build-hooks/hooks/git

@@ -57,7 +57,7 @@ main(){
     get_clone_path "$@"
     pushd $clone_PATH &> /dev/null
     commit_latest=`$REAL_COMMAND log -n 1 | head -n 1| awk '{print$2}'`
-    [ -f $version_file ] && commit=`grep $URL $version_file | awk -F, '{print$2}'`
+    [ -f $version_file ] && commit=`grep $URL $version_file | awk -F== '{print$2}'`
 
     # control version or record version file
     if [[ $ENABLE_VERSION_CONTROL_GIT == "y" ]];then