pylint/pep8 fixes

- android/workload: emoved an extra bank line between methods
- trace_cmd: define member attribute inside __init__
- adb_shell: ignore pylint warning about too many branches in this case

wlauto/common/android/workload.py

@@ -169,7 +169,6 @@ class ApkWorkload(Workload):
         self.apk_version = None
         self.logcat_log = None
 
-
     def init_resources(self, context):
         self.apk_file = context.resolver.get(wlauto.common.android.resources.ApkFile(self),
                                              version=getattr(self, 'version', None),

wlauto/instrumentation/trace_cmd/__init__.py

@@ -155,6 +155,7 @@ class TraceCmdInstrument(Instrument):
     def __init__(self, device, **kwargs):
         super(TraceCmdInstrument, self).__init__(device, **kwargs)
         self.trace_cmd = None
+        self._pull_timeout = None
         self.event_string = _build_trace_events(self.events)
         self.output_file = os.path.join(self.device.working_directory, OUTPUT_TRACE_FILE)
         self.temp_trace_file = self.device.path.join(self.device.working_directory, OUTPUT_TRACE_FILE)

wlauto/utils/android.py

@@ -266,6 +266,7 @@ am_start_error = re.compile(r"Error: Activity class {[\w|.|/]*} does not exist")
 
 
 def adb_shell(device, command, timeout=None, check_exit_code=False, as_root=False):  # NOQA
+    # pylint: disable=too-many-branches
     _check_env()
     if as_root:
         command = 'echo \'{}\' | su'.format(escape_single_quotes(command))