fix: actions would fail on 'charm.run_relation_action' missing.

This is due to the fact that ``stdbuf`` will try to find a direct
process to launch. We must launch bash to make sense of exported
functions.

bin/compose

@@ -1557,7 +1557,7 @@ _run_service_action_direct() {
             export SERVICE_DATASTORE="$DATASTORE/$service"
             export SERVICE_CONFIGSTORE="$CONFIGSTORE/$service"
             exname="$exname $ACTION_NAME $SERVICE_NAME" \
-                    stdbuf -oL -eL charm.run_direct_action "$charm" "$action" "$@"
+                    stdbuf -oL -eL bash -c 'charm.run_direct_action "$@"' -- "$charm" "$action" "$@"
             echo "$?" > "$action_errlvl_file"
         ) | logstdout "$DARKYELLOW$charm$NORMAL/${DARKCYAN}$action${NORMAL} ${GREEN}@${NORMAL}"
     } 3>&1 1>&2 2>&3 | logstderr "$DARKYELLOW$charm$NORMAL/${DARKCYAN}$action${NORMAL} ${RED}@$NORMAL" 3>&1 1>&2 2>&3
@@ -1599,7 +1599,7 @@ _run_service_action_relation() {
             export SERVICE_DATASTORE="$DATASTORE/$service"
             export SERVICE_CONFIGSTORE="$CONFIGSTORE/$service"
             exname="$exname $ACTION_NAME $SERVICE_NAME" \
-                    stdbuf -oL -eL charm.run_relation_action "$charm" "$relation_name" "$action" "$@"
+                    stdbuf -oL -eL bash -c 'charm.run_relation_action "$@"' -- "$target_charm" "$relation_name" "$action" "$@"
             echo "$?" > "$action_errlvl_file"
         ) | logstdout "$DARKYELLOW$charm$NORMAL/${DARKCYAN}$action${NORMAL} ${GREEN}@${NORMAL}"
     } 3>&1 1>&2 2>&3 | logstderr "$DARKYELLOW$charm$NORMAL/${DARKCYAN}$action${NORMAL} ${RED}@$NORMAL" 3>&1 1>&2 2>&3
@@ -1672,14 +1672,14 @@ has_service_action () {
 
     ## Action directly provided ?
 
-    if charm.has_direct_action "$charm" "$action"; then
+    if charm.has_direct_action "$charm" "$action" >/dev/null; then
         echo -en "direct\0$charm" | tee "$cache_file"
         return 0
     fi
     ## Action provided by relation ?
     while read-0 relation_name target_service relation_config tech_dep; do
         target_charm=$(get_service_charm "$target_service") || return 1
-        if charm.has_relation_action "$target_charm" "$relation_name" "$action"; then
+        if charm.has_relation_action "$target_charm" "$relation_name" "$action" >/dev/null; then
             echo -en "relation\0$charm\0$target_charm\0$relation_name\0$relation_config" | tee "$cache_file"
             return 0
         fi