ext: Remove dead code from helper.py

This has been tested with vulture:
https://pypi.org/project/vulture/

Change-Id: I32aad410145dd142bba8e0b9ab912e9c2bad6001
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30235
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

ext/testlib/helper.py

@@ -29,7 +29,7 @@
 '''
 Helper classes for writing tests with this test library.
 '''
-from collections import MutableSet, OrderedDict
+from collections import MutableSet
 
 import difflib
 import errno
@@ -41,9 +41,6 @@ import subprocess
 import tempfile
 import threading
 import time
-import traceback
-
-from six.moves import queue as Queue
 
 #TODO Tear out duplicate logic from the sandbox IOManager
 def log_call(logger, command, *popenargs, **kwargs):
@@ -161,7 +158,6 @@ def cacheresult(function, typed=False):
     .. note:: From cpython 3.7
     '''
     sentinel = object()          # unique object used to signal cache misses
-    make_key = _make_key         # build a key from the function arguments
     cache = {}
     def wrapper(*args, **kwds):
         # Simple caching without ordering or size limit
@@ -350,31 +346,6 @@ def append_dictlist(dict_, key, value):
     list_.append(value)
     dict_[key] = list_
 
-
-class ExceptionThread(threading.Thread):
-    '''
-    Wrapper around a python :class:`Thread` which will raise an
-    exception on join if the child threw an unhandled exception.
-    '''
-    def __init__(self, *args, **kwargs):
-        threading.Thread.__init__(self, *args, **kwargs)
-        self._eq = Queue.Queue()
-
-    def run(self, *args, **kwargs):
-        try:
-            threading.Thread.run(self, *args, **kwargs)
-            self._eq.put(None)
-        except:
-            tb = traceback.format_exc()
-            self._eq.put(tb)
-
-    def join(self, *args, **kwargs):
-        threading.Thread.join(*args, **kwargs)
-        exception = self._eq.get()
-        if exception:
-            raise Exception(exception)
-
-
 def _filter_file(fname, filters):
     with open(fname, "r") as file_:
         for line in file_:
@@ -397,7 +368,6 @@ def _filter_file_inplace(fname, dir, filters):
     Filter the given file writing filtered lines out to a temporary file, then
     copy that tempfile back into the original file.
     '''
-    reenter = False
     (_, tfname) = tempfile.mkstemp(dir=dir, text=True)
     with open(tfname, 'w') as tempfile_:
         for line in _filter_file(fname, filters):