fix(clone): call communicate if there is no progress handler

Previously, it could have happened that pipes ran full, deadlocking the operation

Related to gitpython-developers#72

Author: Byron

git/repo/base.py

@@ -827,6 +827,7 @@ def _clone(cls, git, url, path, odb_default_type, progress, **kwargs):
             if progress:
                 handle_process_output(proc, None, progress.new_message_handler(), finalize_process)
             else:
+                proc.communicate()
                 finalize_process(proc)
             # end handle progress
         finally:

git/test/test_repo.py

@@ -796,4 +796,4 @@ def test_work_tree_unsupported(self, rw_dir):
         worktree_path = join_path_native(rw_dir, 'worktree_repo')
         rw_master.git.worktree('add', worktree_path, 'master')
 
-        self.failUnlessRaises(WorkTreeRepositoryUnsupported, Repo, worktree_path)
+        self.failUnlessRaises(InvalidGitRepositoryError, Repo, worktree_path)