Fixed: "Gun-Triggered Switches Inactive in PWADs" (see here http://so…

…urceforge.net/tracker/?func=detail&atid=542099&aid=2849319&group_id=74815).

doomsday/plugins/common/src/p_map.c

@@ -1560,17 +1560,15 @@ boolean PTR_ShootTraverse(intercept_t* in)
         frontSec = P_GetPtrp(li, DMU_FRONT_SECTOR);
         backSec = P_GetPtrp(li, DMU_BACK_SECTOR);
 
-        if(!frontSec || !backSec)
-        {
-            if(P_PointOnLinedefSide(tracePos[VX], tracePos[VY], li))
-                return true; // Continue traversal.
-
-            goto hitline;
-        }
+        if(!backSec && P_PointOnLinedefSide(tracePos[VX], tracePos[VY], li))
+            return true; // Continue traversal.
 
         if(xline->special)
             P_ActivateLine(li, shootThing, 0, SPAC_IMPACT);
 
+        if(!backSec)
+            goto hitline;
+
 #if __JDOOM64__
         if(xline->flags & ML_BLOCKALL) // jd64
             goto hitline;