fix for crash when running in background mode and adjusting materials

source/blender/blenkernel/intern/icons.c

@@ -49,6 +49,7 @@
 
 #include "BKE_icons.h"
 #include "BKE_utildefines.h"
+#include "BKE_global.h" /* only for G.background test */
 
 #include "BLO_sys_types.h" // for intptr_t support
 
@@ -217,7 +218,7 @@ void BKE_icon_changed(int id)
 {
 	Icon* icon = 0;
 	
-	if (!id) return;
+	if (!id || G.background) return;
 
 	icon = BLI_ghash_lookup(gIcons, SET_INT_IN_POINTER(id));
 	
@@ -239,7 +240,7 @@ int BKE_icon_getid(struct ID* id)
 {
 	Icon* new_icon = 0;
 
-	if (!id)
+	if (!id || G.background)
 		return 0;
 
 	if (id->icon_id)