Downgrade "assign_to_cpuworker failed" to INFO.

Closes ticket 22356

changes/bug22356

@@ -0,0 +1,5 @@
+  o Minor bugfixes (logging, relay):
+    - Downgrade "assigned_to_cpuworker failed" message to INFO-level
+      severity. In every case that can reach it, either a better warning
+      has already been logged, or no warning is warranted. Fixes bug 22356;
+      bugfix on 0.2.6.3-alpha.

src/or/cpuworker.c

@@ -475,7 +475,7 @@ queue_pending_tasks(void)
       return;
 
     if (assign_onionskin_to_cpuworker(circ, onionskin))
-      log_warn(LD_OR,"assign_to_cpuworker failed. Ignoring.");
+      log_info(LD_OR,"assign_to_cpuworker failed. Ignoring.");
   }
 }