What version are you running?
2.5.1.1
What's the URL of the page containing the problem?
http://reviewboard-fedoraserver.rhcloud.com
What steps will reproduce the problem?

Install Review Board 2.5 RC1 ( I had upgraded it over time from 2.0.x)
Install the new 2.5.1.1 packages with easy_install
Run rb-site upgrade /path/to/site


What is the expected output? What do you see instead?
I expect a successful upgrade to complete. Instead, I get:
remote: CommandError: Your models contain changes that Django Evolution cannot resolve automatically.

remote: Rebuilding directory structure

remote: Updating database. This may take a while.

remote: 

remote: The log output below, including warnings and errors,

remote: can be ignored unless upgrade fails.

remote: 

remote: ------------------ <begin log output> ------------------

remote: Creating tables ...

remote: Upgrading Review Board from 2.5 RC1 to 2.5.1.1

remote: There are unapplied evolutions for webapi.

remote: Project signature has changed - an evolution is required

remote: Installing custom SQL ...

remote: Installing indexes ...

remote: Installed 0 object(s) from 0 fixture(s)

remote: The stored evolutions do not completely resolve all model changes.

remote: Run ./manage.py evolve --hint to see a suggestion for the changes required.

remote: 

remote: The following are the changes that could not be resolved:

remote: In model reviews.ReviewRequest:

remote:     Field 'file_attachment_histories' has been added

remote: In model reviews.Group:

remote:     Field 'is_default_group' has been added

remote:     Field 'email_list_only' has been added

remote: In model accounts.ReviewRequestVisit:

remote:     Field 'visibility' has been added

remote:     Meta property 'index_together' has changed

remote: In model attachments.FileAttachment:

remote:     Field 'attachment_revision' has been added

remote:     Field 'attachment_history' has been added

remote: The model diffviewer.FileDiffData has been deleted

remote: In model diffviewer.FileDiff:

remote:     Field 'legacy_diff_hash' has been added

remote:     Field 'legacy_parent_diff_hash' has been added

remote:     In field 'diff_hash':

remote:         Property 'db_column' has changed

remote:         Property 'related_model' has changed

remote:     In field 'parent_diff_hash':

remote:         Property 'db_column' has changed

remote:         Property 'related_model' has changed

remote: -------------------------

What operating system are you using? What browser?
This is installed on OpenShift 2.x, so essentially RHEL 6 with easy_install.

Please provide any additional information below.
rb-site manage -- evolve --hint gives me:
/var/lib/openshift/53bef9524382ecf76d000052/app-root/runtime/dependencies/python/virtenv/lib/python2.7/site-packages/pycrypto-2.6.1-py2.7-linux-x86_64.egg/Crypto/Util/number.py:57: PowmInsecureWarning: Not using mpz_powm_sec.  You should rebuild using libgmp >= 5 to avoid timing attack vulnerability.
----- Evolution for accounts
from django_evolution.mutations import AddField, ChangeMeta

from django.db import models

MUTATIONS = [

    AddField('ReviewRequestVisit', 'visibility', models.CharField, initial=u'V', max_length=1),

    ChangeMeta('ReviewRequestVisit', 'index_together', [(u'user', u'visibility')])

]
----------------------
----- Evolution for attachments
from django_evolution.mutations import AddField

from django.db import models

MUTATIONS = [

    AddField('FileAttachment', 'attachment_revision', models.IntegerField, initial=0),

    AddField('FileAttachment', 'attachment_history', models.ForeignKey, null=True, related_model='attachments.FileAttachmentHistory')

]
----------------------
CommandError: ChangeField does not support modifying the 'related_model' attribute on 'FileDiff.diff_hash'.