--- a/vcssync/mozvcssync/gitrewrite/__init__.py
+++ b/vcssync/mozvcssync/gitrewrite/__init__.py
@@ -8,16 +8,21 @@ import collections
 import json
 import os
 import re
 import stat
 import uuid
 
 import github3.pulls
 
+from ..util import (
+    get_github_client,
+)
+
+
 class RewriteError(Exception):
     """Represents an error that occurred during rewriting."""
 
 
 def prune_directories(object_store, tree_id, directories):
     """Remove directories from a tree, writing the new trees to the store.
 
     An existing Git Tree object defined by ``tree_id`` will be examined for
@@ -351,20 +356,17 @@ def commit_metadata_rewriter(
     on merge commits. By default, the author of the merge commit is used.
     """
     if committer_action not in ('keep', 'use-author', 'use-committer'):
         raise ValueError('committer_action must be one of keep, use-author, '
                          'or use-committer')
 
     author_map = author_map or {}
 
-    github_client = None
-    if github_token:
-        github_client = github3.login(token=github_token)
-
+    github_client = get_github_client(github_token) if github_token else None
     github_org, github_repo = None, None
     github_cache_dir = os.path.join(repo.path, 'github-cache')
 
     if source_repo and source_repo.startswith(b'https://github.com/'):
         orgrepo = source_repo[len(b'https://github.com/'):]
         github_org, github_repo = orgrepo.split(b'/')
 
     if github_client and github_repo and not os.path.exists(github_cache_dir):

--- a/vcssync/mozvcssync/util.py
+++ b/vcssync/mozvcssync/util.py
@@ -1,16 +1,17 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import absolute_import, unicode_literals
 
 import pipes
 
+import github3
 import hglib
 
 
 def run_hg(logger, client, args):
     """Run a Mercurial command through hgclient and log output."""
     logger.warn('executing: hg %s' % ' '.join(map(pipes.quote, args)))
     out = hglib.util.BytesIO()
 
@@ -20,8 +21,17 @@ def run_hg(logger, client, args):
 
     out_channels = {b'o': write, b'e': write}
     ret = client.runcommand(args, {}, out_channels)
 
     if ret:
         raise hglib.error.CommandError(args, ret, out.getvalue(), b'')
 
     return out.getvalue()
+
+
+def get_github_client(token):
+    """Obtain a github3 client using an API token for authentication."""
+
+    gh = github3.GitHub()
+    gh.login(token=token)
+
+    return gh