Disable proxies for tests that clone over http

Cloning via http in tests will break if the user has proxy settings
enabled that don't explicitly exclude the IP address range being used by
the local gerrit instances spun up to test against.

Change-Id: Ic33b72198a85a063d1818f4b318cde2f57e1b1be

git_review/tests/__init__.py

@@ -145,6 +145,9 @@ class BaseGitReviewTestCase(testtools.TestCase, GerritHelpers):
         self._run_gerrit_cli('create-project', '--empty-commit',
                              '--name', 'test/test_project')
 
+        # ensure user proxy conf doesn't interfere with tests
+        os.environ['NO_PROXY'] = '*'
+
         # prepare repository for the testing
         self._run_git('clone', self.project_uri)
         utils.write_to_file(self._dir('test', 'test_file.txt'),