Comment repair; no semantic changes.

Modules/gcmodule.c

@@ -618,9 +618,10 @@ collect(int generation)
 			debug_cycle("collectable", FROM_GC(gc));
 		}
 	}
-	/* Call tp_clear on objects in the collectable set.  This will cause
+	/* Call tp_clear on objects in the unreachable set.  This will cause
 	 * the reference cycles to be broken.  It may also cause some objects
-	 * in finalizers and/or reachable_from_finalizers to be freed */
+	 * in finalizers to be freed.
+	 */
 	delete_garbage(&unreachable, old);
 
 	/* Collect statistics on uncollectable objects found and print