Fix single room cathedral with quest piece (#5321)

Source/levels/drlg_l1.cpp

@@ -1259,14 +1259,20 @@ void PlaceMiniSetRandom(const Miniset &miniset, int rndper)
 Point SelectChamber()
 {
 	int chamber;
-	if (!HasChamber1)
-		chamber = PickRandomlyAmong({ 2, 3 });
-	else if (!HasChamber2)
-		chamber = PickRandomlyAmong({ 3, 1 });
-	else if (!HasChamber3)
-		chamber = PickRandomlyAmong({ 2, 1 });
-	else
+	if (HasChamber1 && HasChamber2 && HasChamber3) {
 		chamber = GenerateRnd(3) + 1;
+	} else if (HasChamber1 && HasChamber2) {
+		chamber = PickRandomlyAmong({ 2, 1 }); // Reverse order to match vanilla
+	} else if (HasChamber1 && HasChamber3) {
+		chamber = PickRandomlyAmong({ 3, 1 }); // Reverse order to match vanilla
+	} else if (HasChamber2 && HasChamber3) {
+		chamber = PickRandomlyAmong({ 2, 3 });
+	} else {
+		// The dungeon generation logic ensures that chamber 2 is available if
+		// either (or both of) 1 or 3 aren't, so if we ever end up with a single
+		// chamber layout it's always chamber 2.
+		chamber = 2;
+	}
 
 	switch (chamber) {
 	case 1:

test/Fixtures.cmake

@@ -32,6 +32,7 @@ set(devilutionx_fixtures
   hellfire/1-536340718.dun
   hellfire/2-128964898.dun
   hellfire/2-1180526547.dun
+  hellfire/3-1369955278.dun
   hellfire/3-1512491184.dun
   hellfire/3-1799396623.dun
   hellfire/4-1190318991.dun

test/drlg_l1_test.cpp

@@ -148,6 +148,22 @@ TEST(Drlg_l1, CreateL5Dungeon_hellfire_2_1180526547)
 	EXPECT_EQ(ViewPosition, Point(81, 45));
 }
 
+TEST(Drlg_l1, CreateL5Dungeon_hellfire_3_1369955278)
+{
+	LoadExpectedLevelData("hellfire/3-1369955278.dun");
+
+	Players.resize(1);
+	MyPlayer = &Players[0];
+	MyPlayer->pOriginalCathedral = false;
+	InitQuests();
+	Quests[Q_SKELKING]._qactive = QUEST_INIT;
+
+	TestCreateDungeon(3, 1369955278, ENTRY_MAIN);
+	EXPECT_EQ(ViewPosition, Point(63, 86));
+	TestCreateDungeon(3, 1369955278, ENTRY_PREV);
+	EXPECT_EQ(ViewPosition, Point(75, 69));
+}
+
 TEST(Drlg_l1, CreateL5Dungeon_hellfire_3_1799396623)
 {
 	LoadExpectedLevelData("hellfire/3-1799396623.dun");