use GitPython instead of pygit2

Author: Vladimir Kotal

opengrok-tools/requirements.txt

@@ -11,3 +11,4 @@ requests==2.20.0
 Resource==0.2.1
 six==1.11.0
 urllib3==1.23
+GitPython==3.0.2

opengrok-tools/setup.py

@@ -45,7 +45,7 @@ def readme():
     ],
     tests_require=[
         'pytest',
-        'pygit2',
+        'GitPython',
         'pytest-xdist',
     ],
     entry_points={

opengrok-tools/src/test/python/test_mirror.py

@@ -27,7 +27,7 @@
 import tempfile
 import os
 import stat
-import pygit2
+from git import Repo
 import pytest
 import sys
 
@@ -154,8 +154,8 @@ def mock_get(*args, **kwargs):
             return MockResponse()
 
         # Clone a Git repository so that it can pull.
-        pygit2.init_repository(repo_path, True)
-        pygit2.clone_repository(repo_path, cloned_repo_path)
+        repo = Repo.init(repo_path)
+        repo.clone(cloned_repo_path)
 
         with monkeypatch.context() as m:
             m.setattr(sys, 'argv', ['prog', "-I", project_name])