Simplify getting identity

setup_main_tex_file.py

@@ -78,7 +78,7 @@ def git_integration(func):
             master_add_paths = [fp for fp in repo_status
                     if (fp.startswith('content/') or fp.startswith('slides/')) and repo_status[fp] in to_add_status]
 
-            author = pygit2.Signature(repo.config['user.name'], repo.config['user.email'])
+            author = repo.default_signature
             committer = author
 
             index = repo.index