When generate.sh fails its rc=0 - take 2

patch by Andres de la Peña and Berenguer Blasi; reviewed by Andres de la Peña for CASSANDRA-18032

Co-authored-by: Berenguer Blasi <berenguerblasi@gmail.com>
Co-authored-by: Andres de la Peña <a.penya.garcia@gmail.com>

.circleci/generate.sh

@@ -190,7 +190,8 @@ if (!($all)); then
            | sed -e "s/\\.java//" \
            | sed -e "s,^${2},," \
            | tr  '/' '.' \
-           | grep ${3} )
+           | grep ${3} )\
+           || : # avoid execution interruptions due to grep return codes and set -e
     for test in $tests; do
       echo "  $test"
       has_env_vars=true