Revert "Merge pull request apache#57 from Shopify/do_not_shrink_shuffle_batch_size"

This reverts commit 044b478, reversing
changes made to b68a83b.

Author: airhorns

python/pyspark/shuffle.py

@@ -513,6 +513,7 @@ def load(f):
                 chunks.append(load(open(path, 'rb')))
                 current_chunk = []
                 gc.collect()
+                batch //= 2
                 limit = self._next_limit()
                 MemoryBytesSpilled += max(used_memory - get_used_memory(), 0) << 20
                 DiskBytesSpilled += os.path.getsize(path)