What version are you running?
ReviewBoard 2.5.8
What's the URL of the page containing the problem?
/reviews/
What steps will reproduce the problem?

Load main review requests list on ReviewBoard 2.5.8

What is the expected output? What do you see instead?
Expected: page. Result: 500 internal server error
What operating system are you using? What browser?
RHEL 6, Python 2.6.6
pytz module version 2010h  (I used easy_install --upgrade ReviewBoard to go from ReviewBoard 2.5.7 to 2.5.8, and the ReviewBoard dependencies are such that easy_install didn't see a need to upgrade pytz from this version)
Please provide any additional information below.
Part of the the traceback from wsgi log:
ERROR:root:Unable to load webapi resource review_request: No module named exceptions

Traceback (most recent call last):

  File "/usr/lib/python2.6/site-packages/Djblets-0.9.5-py2.6.egg/djblets/webapi/resources/registry.py", line 65, in getattr

    {}, {}, [instance_name])

  File "/usr/lib/python2.6/site-packages/ReviewBoard-2.5.8-py2.6.egg/reviewboard/webapi/resources/review_request.py", line 22, in <module>

    from pytz.exceptions import AmbiguousTimeError

ImportError: No module named exceptions
Looking at the code, it's because in pytz version 2010h has AmbiguousTimeError class defined in pytz.tzinfo, not pytz.exceptions
This diff fixes the problem:
--- /usr/lib/python2.6/site-packages/ReviewBoard-2.5.8-py2.6.egg/reviewboard/webapi/resources/review_request.py.orig    2017-02-10 14:27:23.143549455 +0000

+++ /usr/lib/python2.6/site-packages/ReviewBoard-2.5.8-py2.6.egg/reviewboard/webapi/resources/review_request.py 2017-02-10 14:27:53.475549455 +0000

@@ -19,7 +19,7 @@

                                    INVALID_FORM_DATA,

                                    NOT_LOGGED_IN,

                                    PERMISSION_DENIED)

-from pytz.exceptions import AmbiguousTimeError

+from pytz.tzinfo import AmbiguousTimeError
from reviewboard.admin.server import build_server_url

 from reviewboard.diffviewer.errors import (DiffTooBigError,