Rails 2 and Rails 3 in the same gemset leads to errors

Hi.

I am pretty new to ruby (and those gems) and rails.. Until now I
thought that all rails application have some kind of integrated
version management (RAILS_GEM_VERSION in Rails 2 and gem 'rails' in
Rails 3). And therefore I thought that having Rails 2 and Rails 3 in
the same gem repository (in my case gemset under rvm) wouldn't be a
problem. But during installing Redmine I figured out that it can lead
to problems. When Rails 2 and Rails 3 are in the same gemset Redmine
cashes on some pages that when only Rails 2 is in the gemset doesn't
happen. So it seems that Redmine does use some things of the Rails 3
libraries even though it specifies the correct RAILS_GEM_VERSION of
2.3.5. Why that?

Best regards,
Kai

The error trace:

Processing MyController#account (for x.x.x.x at 2010-08-13 17:15:52)
[GET]
  Parameters: {"action"=>"account", "controller"=>"my"}
Rendering template within layouts/base
Rendering my/account
DEPRECATION WARNING: using %d in messages is deprecated; use {{count}}
instead.. (called from interpolate at /var/www/vhosts/
mydomain.org/.rvm/gems/ruby-1.8.7-p299/gems/activerecord-2.3.5/lib/
active_record/i18n_interpolation_deprecation.rb:17)

ActionView::TemplateError (missing interpolation argument in "%m/%
{count}/%Y %I:%M %p" ({:object=>Fri Aug 13 16:15:41 +0200 2010}
given)) on line #4 of app/views/my/_sidebar.rhtml:
1: <h3><%=l(:label_my_account)%></h3>
2:
3: <p><%=l(:field_login)%>: <strong><%= @user.login %></strong><br />
4: <%=l(:field_created_on)%>: <%= format_time(@user.created_on) %></p>
5:
6:
7: <h4><%= l(:label_feeds_access_key) %></h4>

    /var/www/vhosts/mydomain.org/.rvm/gems/ruby-1.8.7-p299/gems/
i18n-0.4.1/lib/i18n/backend/base.rb:186:in
`interpolate_without_deprecated_syntax'
    /var/www/vhosts/mydomain.org/.rvm/gems/ruby-1.8.7-p299/gems/
i18n-0.4.1/lib/i18n/backend/base.rb:49:in `translate'
    /var/www/vhosts/mydomain.org/.rvm/gems/ruby-1.8.7-p299/gems/
i18n-0.4.1/lib/i18n.rb:152:in `t'
    /var/www/vhosts/mydomain.org/.rvm/gems/ruby-1.8.7-p299/gems/
i18n-0.4.1/lib/i18n/backend/base.rb:62:in `localize'
    /var/www/vhosts/mydomain.org/.rvm/gems/ruby-1.8.7-p299/gems/
i18n-0.4.1/lib/i18n.rb:231:in `l'
    lib/redmine/i18n.rb:48:in `format_time'
    app/views/my/_sidebar.rhtml:4:in
`_run_rhtml_app47views47my47_sidebar46rhtml_locals_object_sidebar'
    app/views/my/account.rhtml:59:in
`_run_rhtml_app47views47my47account46rhtml'
    app/helpers/application_helper.rb:764:in `content_for'
    app/views/my/account.rhtml:58:in
`_run_rhtml_app47views47my47account46rhtml'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/httpserver.rb:104:in `service'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/httpserver.rb:65:in `run'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:173:in `start_thread'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:162:in `start'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:162:in `start_thread'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:95:in `start'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:92:in `each'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:92:in `start'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:23:in `start'
    /var/www/vhosts/mydomain.org/.rvm/rubies/ruby-1.8.7-p299/lib/ruby/
1.8/webrick/server.rb:82:in `start'

Rendering /var/www/vhosts/mydomain.org/rails/redmine-1.0/public/
500.html (500 Internal Server Error)