Revert "Revert "Remove chunk size for url stream""

This reverts commit d2431b9523.

This didn't really have an effect on memory usage, however it did
increase overall log size since we now show each 1meg chunk request when
running under --debug.

Change-Id: I526dcd3e8365e710cf94093728165d1f29135516

tripleo_common/image/image_uploader.py

@@ -1798,7 +1798,8 @@ class PythonImageUploader(BaseImageUploader):
         }
         source_blob_url = cls._build_url(
             source_url, CALL_BLOB % parts)
-        chunk_size = 2 ** 20
+        # NOTE(aschultz): We specify None and let requests figure it out
+        chunk_size = None
         LOG.info("[%s] Fetching layer %s from %s" %
                  (image, digest, source_blob_url))
         with session.get(source_blob_url,