Work around pdnsmysql connection freezes

lib/functions.sh

@@ -396,6 +396,16 @@ start_service() {
           kill -9 $SPINPID &> /dev/null
           fail "There was a problem starting service /federated/apps/$SERVICE\nCheck the output of 'docker logs $SERVICE' or turn on\ndebug with set -x"
         fi
+        if [ "$SERVICE" = "pdnsmysql" ]; then
+          # Workaround for an obscure bug where network connections from the outside aren't
+          # accepted until a network connection has been created from the inside.
+          # Seems to occur at semi-random, more frequently with docker 27.5.1
+          # A simple ping -c1 1.1.1.1 would probably be sufficient, but ping and
+          # friends don't exist in the mariadb container
+	  # FIXME we should fix this properly instead of applying this workaround
+	  # some time.
+          docker exec -ti $SERVICE apt update
+        fi
         ((RETRY--))
         sleep 7
       fi