factory: Use imp.reload instead of builtin reload function

Because builtin `reload()` is deprecated in python3.

BUG=chromium:999876
TEST=make test

Change-Id: I6579b2f5304c444c9ff26997cfed4555a11082a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/factory/+/1894780
Reviewed-by: Yong Hong <yhong@chromium.org>
Commit-Queue: Yilin Yang <kerker@chromium.org>
Tested-by: Yilin Yang <kerker@chromium.org>
Auto-Submit: Yilin Yang <kerker@chromium.org>
diff --git a/py/instalog/plugin_loader.py b/py/instalog/plugin_loader.py
index e8f368b..ea93332 100644
--- a/py/instalog/plugin_loader.py
+++ b/py/instalog/plugin_loader.py
@@ -12,6 +12,7 @@
 
 from __future__ import print_function
 
+import imp
 import inspect
 import logging
 import sys
@@ -127,7 +128,7 @@
           # Why?  In the case that the file no longer exists on re-import,
           # __import__ would silently ignore and pass a reference to the old
           # module, but reload throws an ImportError.
-          return reload(sys.modules[search_name])
+          return imp.reload(sys.modules[search_name])
 
         __import__(search_name)
         return sys.modules[search_name]
diff --git a/py/test/utils/pytest_utils_unittest.py b/py/test/utils/pytest_utils_unittest.py
index a217a7b..8bf5745 100755
--- a/py/test/utils/pytest_utils_unittest.py
+++ b/py/test/utils/pytest_utils_unittest.py
@@ -3,6 +3,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import imp
 import os
 import shutil
 import sys
@@ -50,10 +51,10 @@
 
   def ReloadPytestModules(self):
     module = sys.modules[_PYTEST_MODULES[0]]
-    reload(module)
+    imp.reload(module)
     for submodule in _PYTEST_MODULES[1:]:
       module = getattr(module, submodule)
-      reload(module)
+      imp.reload(module)
 
 
   def setUp(self):