manager/service: when we have multiple candidates to handle, warn

This would be very confusing to users, so let's warn if they configured the
same handler for multiple units and we're not running it as expected.

diff --git a/src/core/service.c b/src/core/service.c
index f5fe683cf2f72b199c961e527d9037a08eaa9bb3..942bc7c0ff71f33ae91a2cef9b74f6c329c07001 100644 (file)
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -1462,24 +1462,23 @@ static Service *service_get_triggering_service(Service *s) {
          * one to propagate the exit status. */
 
         UNIT_FOREACH_DEPENDENCY(other, UNIT(s), UNIT_ATOM_ON_FAILURE_OF) {
-                if (candidate) {
-                        log_unit_debug(UNIT(s), "multiple trigger source candidates for exit status propagation, skipping.");
-                        return NULL;
-                }
-
+                if (candidate)
+                        goto have_other;
                 candidate = other;
         }
 
         UNIT_FOREACH_DEPENDENCY(other, UNIT(s), UNIT_ATOM_ON_SUCCESS_OF) {
-                if (candidate) {
-                        log_unit_debug(UNIT(s), "multiple trigger source candidates for exit status propagation, skipping.");
-                        return NULL;
-                }
-
+                if (candidate)
+                        goto have_other;
                 candidate = other;
         }
 
         return SERVICE(candidate);
+
+ have_other:
+        log_unit_warning(UNIT(s), "multiple trigger source candidates for exit status propagation (%s, %s), skipping.",
+                         candidate->id, other->id);
+        return NULL;
 }
 
 static int service_spawn_internal(