Some improvements (#846)

* #833: do not require sudo on TravisCI

* #N/A: Add Python dev releases to TravisCI pipeline

Inspired by Brett Cannon's advise [1].

    1: https://snarky.ca/how-to-use-your-project-travis-to-help-test-python-itself/

* #837: try and kill proc and its children

* #N/A: show shell information on `thefuck --version`

* #N/A: omit default arguments to get_close_matches

* #842: add settings var to control number of close matches

* #N/A: remove `n` from the list of `get_closest`'s args

tests/output_readers/test_rerun.py

@@ -0,0 +1,58 @@
+# -*- encoding: utf-8 -*-
+
+from mock import Mock, patch
+from psutil import AccessDenied, TimeoutExpired
+
+from thefuck.output_readers import rerun
+
+
+class TestRerun(object):
+    def setup_method(self, test_method):
+        self.patcher = patch('thefuck.output_readers.rerun.Process')
+        process_mock = self.patcher.start()
+        self.proc_mock = process_mock.return_value = Mock()
+
+    def teardown_method(self, test_method):
+        self.patcher.stop()
+
+    @patch('thefuck.output_readers.rerun._wait_output', return_value=False)
+    @patch('thefuck.output_readers.rerun.Popen')
+    def test_get_output(self, popen_mock, wait_output_mock):
+        popen_mock.return_value.stdout.read.return_value = b'output'
+        assert rerun.get_output('', '') is None
+        wait_output_mock.assert_called_once()
+
+    def test_wait_output_is_slow(self, settings):
+        assert rerun._wait_output(Mock(), True)
+        self.proc_mock.wait.assert_called_once_with(settings.wait_slow_command)
+
+    def test_wait_output_is_not_slow(self, settings):
+        assert rerun._wait_output(Mock(), False)
+        self.proc_mock.wait.assert_called_once_with(settings.wait_command)
+
+    @patch('thefuck.output_readers.rerun._kill_process')
+    def test_wait_output_timeout(self, kill_process_mock):
+        self.proc_mock.wait.side_effect = TimeoutExpired(3)
+        self.proc_mock.children.return_value = []
+        assert not rerun._wait_output(Mock(), False)
+        kill_process_mock.assert_called_once_with(self.proc_mock)
+
+    @patch('thefuck.output_readers.rerun._kill_process')
+    def test_wait_output_timeout_children(self, kill_process_mock):
+        self.proc_mock.wait.side_effect = TimeoutExpired(3)
+        self.proc_mock.children.return_value = [Mock()] * 2
+        assert not rerun._wait_output(Mock(), False)
+        assert kill_process_mock.call_count == 3
+
+    def test_kill_process(self):
+        proc = Mock()
+        rerun._kill_process(proc)
+        proc.kill.assert_called_once_with()
+
+    @patch('thefuck.output_readers.rerun.logs')
+    def test_kill_process_access_denied(self, logs_mock):
+        proc = Mock()
+        proc.kill.side_effect = AccessDenied()
+        rerun._kill_process(proc)
+        proc.kill.assert_called_once_with()
+        logs_mock.debug.assert_called_once()