Redmine

When viewing the Settings for a project I'm getting this error:

NoMethodError in Projects#settings

Showing app/views/projects/settings/_members.rhtml where line #3 raised:

undefined method `<=>' for nil:NilClass

Extracted source (around line #3):

1: <%= error_messages_for 'member' %>
2: <% roles = Role.find_all_givable
3:    members = @project.member_principals.find(:all, :include => [:roles, :principal]).sort %>
4: 
5: <div class="splitcontentleft">
6: <% if members.any? %>

LOCAL GEMS

abstract (1.0.0)
actionmailer (2.3.5, 2.3.2)
actionpack (2.3.5, 2.3.2)
activerecord (2.3.5, 2.3.2)
activeresource (2.3.5, 2.3.2)
activesupport (2.3.5, 2.3.2)
arel (1.0.1)
builder (2.1.2)
bundler (1.0.0)
erubis (2.6.6)
fastthread (1.0.7)
i18n (0.3.7)
mail (2.2.5)
mime-types (1.16)
mysql (2.8.1)
passenger (2.2.15)
polyglot (0.3.1)
rack (1.2.1, 1.0.1)
rack-mount (0.6.13)
rack-test (0.5.4)
rails (2.3.5, 2.3.2)
rake (0.8.7, 0.8.3)
rubygems-update (1.3.7)
thor (0.14.0)
treetop (1.4.8)
tzinfo (0.3.23)

Using r3559.

Only one project is affected, other project settings can be viewed/modified without issue.