[autotest] Make resource_monitor_unittest.py Python3-compatible syntax-wise.

The except clause 'except ValueError, IndexError' is a mistake. In Python 2,
this catches a ValueError by the name IndexError. Fixing the bug makes
this code Python3-compatible. Because this is a semantic change, I'm separating
it out from the rest of changes.

BUG=chromium:990593
TEST=python3 -m py_compile cros/resource_monitor_unittest.py

Change-Id: Ic3f3419720a78f6baab305c4b91027760adb335f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2298817
Tested-by: Gregory Nisbet <gregorynisbet@google.com>
Commit-Queue: Ilja H. Friedel <ihf@chromium.org>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
diff --git a/server/cros/resource_monitor_unittest.py b/server/cros/resource_monitor_unittest.py
index c6cf9d67..d5065a6 100644
--- a/server/cros/resource_monitor_unittest.py
+++ b/server/cros/resource_monitor_unittest.py
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+from __future__ import print_function
+
 import logging
 import unittest
 import re
@@ -64,7 +66,7 @@
         try:
             self.redirect_index = cmd_args.index(">")
             self.top_output_file_path = cmd_args[self.redirect_index + 1]
-        except ValueError, IndexError:
+        except (ValueError, IndexError):
             self.called_unsupported_command(cmd_line)
 
         self.top_is_running = True