Use Rails edge as dependency.

Gemfile

@@ -10,9 +10,9 @@ DM_VERSION   = '~> 1.0.2'
 group :runtime do
 
   gem 'i18n',           '~> 0.5.0'
-  gem 'activesupport',  '~> 3.0.4', :require => 'active_support'
-  gem 'actionpack',     '~> 3.0.4', :require => 'action_pack'
-  gem 'railties',       '~> 3.0.4', :require => 'rails'
+  gem 'activesupport',  :git => 'git://github.com/rails/rails.git', :require => 'active_support'
+  gem 'actionpack',     :git => 'git://github.com/rails/rails.git', :require => 'action_pack'
+  gem 'railties',       :git => 'git://github.com/rails/rails.git', :require => 'rails'
   gem 'dm-core',         DM_VERSION, SOURCE => "#{DATAMAPPER}/dm-core#{REPO_POSTFIX}"
   gem 'dm-active_model', DM_VERSION, SOURCE => "#{DATAMAPPER}/dm-active_model#{REPO_POSTFIX}"
 

dm-rails.gemspec

@@ -73,19 +73,19 @@ Gem::Specification.new do |s|
 
     if Gem::Version.new(Gem::VERSION) >= Gem::Version.new('1.2.0') then
       s.add_runtime_dependency(%q<i18n>, ["~> 0.5.0"])
-      s.add_runtime_dependency(%q<activesupport>, ["~> 3.0.4"])
-      s.add_runtime_dependency(%q<actionpack>, ["~> 3.0.4"])
-      s.add_runtime_dependency(%q<railties>, ["~> 3.0.4"])
+      s.add_runtime_dependency(%q<activesupport>, [">= 0"])
+      s.add_runtime_dependency(%q<actionpack>, [">= 0"])
+      s.add_runtime_dependency(%q<railties>, [">= 0"])
       s.add_runtime_dependency(%q<dm-core>, ["~> 1.0.2"])
       s.add_runtime_dependency(%q<dm-active_model>, ["~> 1.0.2"])
       s.add_development_dependency(%q<rake>, ["~> 0.8.7"])
       s.add_development_dependency(%q<jeweler>, ["~> 1.5.2"])
       s.add_development_dependency(%q<rspec>, ["~> 1.3.1"])
     else
       s.add_dependency(%q<i18n>, ["~> 0.5.0"])
-      s.add_dependency(%q<activesupport>, ["~> 3.0.4"])
-      s.add_dependency(%q<actionpack>, ["~> 3.0.4"])
-      s.add_dependency(%q<railties>, ["~> 3.0.4"])
+      s.add_dependency(%q<activesupport>, [">= 0"])
+      s.add_dependency(%q<actionpack>, [">= 0"])
+      s.add_dependency(%q<railties>, [">= 0"])
       s.add_dependency(%q<dm-core>, ["~> 1.0.2"])
       s.add_dependency(%q<dm-active_model>, ["~> 1.0.2"])
       s.add_dependency(%q<rake>, ["~> 0.8.7"])
@@ -94,9 +94,9 @@ Gem::Specification.new do |s|
     end
   else
     s.add_dependency(%q<i18n>, ["~> 0.5.0"])
-    s.add_dependency(%q<activesupport>, ["~> 3.0.4"])
-    s.add_dependency(%q<actionpack>, ["~> 3.0.4"])
-    s.add_dependency(%q<railties>, ["~> 3.0.4"])
+    s.add_dependency(%q<activesupport>, [">= 0"])
+    s.add_dependency(%q<actionpack>, [">= 0"])
+    s.add_dependency(%q<railties>, [">= 0"])
     s.add_dependency(%q<dm-core>, ["~> 1.0.2"])
     s.add_dependency(%q<dm-active_model>, ["~> 1.0.2"])
     s.add_dependency(%q<rake>, ["~> 0.8.7"])