Fix import order and disable broad-except pylint warning. (#788)

* Fix import order and disable broad-except pylint warning.

* Disable broad-except pylint warning in utils._kill_process_tree.

Co-authored-by: Ang Li <angli@google.com>
diff --git a/mobly/utils.py b/mobly/utils.py
index cef70fa..6015617 100644
--- a/mobly/utils.py
+++ b/mobly/utils.py
@@ -30,11 +30,11 @@
 import threading
 import time
 import traceback
-from typing import overload, Tuple
-# TODO(ericth): Use Literal from typing if we only run on Python 3.8 or later.
-from typing_extensions import Literal
+from typing import Tuple, overload
 
 import portpicker
+# TODO(ericth): Use Literal from typing if we only run on Python 3.8 or later.
+from typing_extensions import Literal
 
 # File name length is limited to 255 chars on some OS, so we need to make sure
 # the file names we output fits within the limit.
@@ -313,13 +313,13 @@
   for child_pid in _collect_process_tree(proc.pid):
     try:
       os.kill(child_pid, signal.SIGTERM)
-    except Exception:
+    except Exception:  # pylint: disable=broad-except
       failed.append(child_pid)
       logging.exception('Failed to kill standing subprocess %d', child_pid)
 
   try:
     proc.kill()
-  except Exception:
+  except Exception:  # pylint: disable=broad-except
     failed.append(proc.pid)
     logging.exception('Failed to kill standing subprocess %d', proc.pid)
 
@@ -362,7 +362,7 @@
       params = future_to_params[future]
       try:
         return_vals.append(future.result())
-      except Exception as exc:
+      except Exception as exc:  # pylint: disable=broad-except
         logging.exception('%s generated an exception: %s', params,
                           traceback.format_exc())
         return_vals.append(exc)