Updated Upstream (Bukkit/CraftBukkit/Spigot)

Upstream has released updates that appears to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing

Bukkit Changes:
79f6ba25 Skip tests on default builds
b85cc32f Further discourage World.regenerateChunk

CraftBukkit Changes:
7560d3b5 Skip tests on default builds
d0a9130d SPIGOT-4563: Fix regenerating chunks saved to disk already

Spigot Changes:
8173d06f Remove need for redundant second clone of repositories
8ede0393 Rebuild patches

Spigot-Server-Patches/Chunk-save-queue-improvements.patch

@@ -53,7 +53,7 @@ index b0c004b1f..d2cece265 100644
          return a(this.x, this.z);
      }
 diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
-index 63533d237..c0785eea0 100644
+index 35976a26f..21ee154a5 100644
 --- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 +++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 @@ -0,0 +0,0 @@ import java.util.Map.Entry;
@@ -95,9 +95,9 @@ index 63533d237..c0785eea0 100644
      private final DataFixer d;
      private PersistentStructureLegacy e;
 @@ -0,0 +0,0 @@ public class ChunkRegionLoader implements IChunkLoader, IAsyncChunkSaver {
- 
-     @Nullable
-     private NBTTagCompound a(DimensionManager dimensionmanager, @Nullable PersistentCollection persistentcollection, int i, int j, @Nullable GeneratorAccess generatoraccess) throws IOException {
+             return null;
+         }
+         // CraftBukkit end
 -        NBTTagCompound nbttagcompound = SupplierUtils.getIfExists(this.b.get(new ChunkCoordIntPair(i, j))); // Spigot
 +        NBTTagCompound nbttagcompound = SupplierUtils.getIfExists(this.saveMap.get(ChunkCoordIntPair.asLong(i, j))); // Spigot // Paper