Index: trunk/src/thermal.c
===================================================================
--- trunk/src/thermal.c	(revision 38600)
+++ trunk/src/thermal.c	(revision 38601)
@@ -831,7 +831,7 @@
 			return NULL;
 	}
 
-	if (gclearance <= 0)
+	if (gclearance <= 0) /* global clearance overrides */
 		clearance = shp->clearance/2;
 	else
 		clearance = gclearance;