Merge "adb: hopefully deflake test_adb.py." am: 151499e4

        with fake_adbd() as (port, _):

            serial = "localhost:{}".format(port)

            with adb_connect(self, serial):

                # Wait a bit to give adb some time to connect.

                time.sleep(0.25)

                output = subprocess.check_output(["adb", "-s", serial,

                                                  "get-state"])

                self.assertEqual(output.strip(), b"device")