Fix revision cooking errors with the vault for large revision log

This fixes a vault issue similar to a one that happened when cooking a directory (#1177 (closed)).

When cooking a gitfast archive for a given revision, fetching the associated revision log must be performed client-side in a paginated way to avoid storage timeouts when the total number of revisions to fetch is pretty large.

Related T1934

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Migrated from D1778 (view on Phabricator)

swh/vault/cookers/revision_flat.py

-# Copyright (C) 2016-2017  The Software Heritage developers
+# Copyright (C) 2016-2019  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -9,6 +9,7 @@ from pathlib import Path
 
 from swh.model import hashutil
 from swh.vault.cookers.base import BaseVaultCooker
+from swh.vault.cookers.utils import revision_log
 from swh.vault.to_disk import DirectoryBuilder
 
 
@@ -22,7 +23,7 @@ class RevisionFlatCooker(BaseVaultCooker):
     def prepare_bundle(self):
         with tempfile.TemporaryDirectory(prefix='tmp-vault-revision-') as td:
             root = Path(td)
-            for revision in self.storage.revision_log([self.obj_id]):
+            for revision in revision_log(self.storage, self.obj_id):
                 revdir = root / hashutil.hash_to_hex(revision['id'])
                 revdir.mkdir()
                 directory_builder = DirectoryBuilder(