Prevent repair droids refusing to retreat

Repair droids that have the "Accept Retreating Units" suborder enabled now ignore other repair units when retreating. This prevents traffic jams when clusters of these units are attacked and then "retreat" to each other. Repair droids with the suborder disabled still retreat to units with the suborder enabled.

src/order.cpp

@@ -3349,25 +3349,33 @@ static inline RtrBestResult decideWhereToRepairAndBalance(DROID *psDroid)
 		}
 	}
 
-	// one of these lists is empty when on mission
-	DROID* psdroidList = apsDroidLists[psDroid->player] != nullptr ? apsDroidLists[psDroid->player] : mission.apsDroidLists[psDroid->player];
-	for (DROID* psCurr = psdroidList; psCurr != nullptr; psCurr = psCurr->psNext)
+	// If we are repair droid ourselves that accept retreating units, don't consider 
+	// other repairs droids. Since this would cause traffic jams if we are attacked amongst
+	// other accepting repair droids. Thus causing chaos as repair units simply clump up
+	// instead of actually retreating.
+	if (!((psDroid->droidType == DROID_REPAIR || psDroid->droidType == DROID_CYBORG_REPAIR)
+		&& secondaryGetState(psDroid, DSO_ACCEPT_RETREP)))
 	{
-		// Accept any repair droids that accept retreating units
-		if ((psCurr->droidType == DROID_REPAIR || psCurr->droidType == DROID_CYBORG_REPAIR)
-			&& secondaryGetState(psCurr, DSO_ACCEPT_RETREP))
+		// one of these lists is empty when on mission
+		DROID* psdroidList = apsDroidLists[psDroid->player] != nullptr ? apsDroidLists[psDroid->player] : mission.apsDroidLists[psDroid->player];
+		for (DROID* psCurr = psdroidList; psCurr != nullptr; psCurr = psCurr->psNext)
 		{
-			thisDistToRepair = droidSqDist(psDroid, psCurr);
-			if (thisDistToRepair <= 0)
-			{
-				continue; // unreachable
-			}
-			vDroidPos.push_back(psCurr->pos);
-			vDroid.push_back(psCurr);
-			if (bestDistToRepairDroid > thisDistToRepair)
+			// Accept any repair droids that accept retreating units
+			if ((psCurr->droidType == DROID_REPAIR || psCurr->droidType == DROID_CYBORG_REPAIR)
+				&& secondaryGetState(psCurr, DSO_ACCEPT_RETREP))
 			{
-				bestDistToRepairDroid = thisDistToRepair;
-				bestDroidPos = psCurr->pos;
+				thisDistToRepair = droidSqDist(psDroid, psCurr);
+				if (thisDistToRepair <= 0)
+				{
+					continue; // unreachable
+				}
+				vDroidPos.push_back(psCurr->pos);
+				vDroid.push_back(psCurr);
+				if (bestDistToRepairDroid > thisDistToRepair)
+				{
+					bestDistToRepairDroid = thisDistToRepair;
+					bestDroidPos = psCurr->pos;
+				}
 			}
 		}
 	}