win: GC after every TC to fixes appveyor hang runs

+ Fixed the hangs at `test_git:TestGit.test_handle_process_output()`.
[travisci skip]

git/test/lib/helper.py

@@ -299,6 +299,8 @@ def setUpClass(cls):
         Dynamically add a read-only repository to our actual type. This way
         each test type has its own repository
         """
+        import gc
+        gc.collect()
         cls.rorepo = Repo(GIT_REPO)
 
     @classmethod

git/test/performance/test_commit.py

@@ -17,6 +17,10 @@
 
 class TestPerformance(TestBigRepoRW):
 
+    def tearDown(self):
+        import gc
+        gc.collect()
+
     # ref with about 100 commits in its history
     ref_100 = '0.1.6'
 

git/test/test_docs.py

@@ -11,6 +11,11 @@
 
 
 class Tutorials(TestBase):
+
+    def tearDown(self):
+        import gc
+        gc.collect()
+
     @with_rw_directory
     def test_init_repo_object(self, rw_dir):
         # [1-test_init_repo_object]
@@ -64,7 +69,7 @@ def test_init_repo_object(self, rw_dir):
         assert repo.head.ref == repo.heads.master                   # head is a symbolic reference pointing to master
         assert repo.tags['0.3.5'] == repo.tag('refs/tags/0.3.5')    # you can access tags in various ways too
         assert repo.refs.master == repo.heads['master']             # .refs provides access to all refs, i.e. heads ...
-        
+
         if 'TRAVIS' not in os.environ:
             assert repo.refs['origin/master'] == repo.remotes.origin.refs.master  # ... remotes ...
         assert repo.refs['0.3.5'] == repo.tags['0.3.5']             # ... and tags

git/test/test_git.py

@@ -40,6 +40,10 @@ def setUpClass(cls):
         super(TestGit, cls).setUpClass()
         cls.git = Git(cls.rorepo.working_dir)
 
+    def tearDown(self):
+        import gc
+        gc.collect()
+
     @patch.object(Git, 'execute')
     def test_call_process_calls_execute(self, git):
         git.return_value = ''