Ensure that recent Rails upgrade doesn't break compatibility with older versions of Rubygems (such as exist in Debian Lenny). Closes #145.

2 files changed, 48 insertions, 0 deletions

diff --git a/config/environment.rb b/config/environment.rb
index 606472740..73cab9201 100644
--- a/config/environment.rb
+++ b/config/environment.rb
@@ -28,6 +28,12 @@ load "config.rb"
 load "format.rb"
 load "debug_helpers.rb"
 load "util.rb"
+# Patch Rails::GemDependency to cope with older versions of rubygems, e.g. in Debian Lenny
+# Restores override removed in https://github.com/rails/rails/commit/c20a4d18e36a13b5eea3155beba36bb582c0cc87
+# without effecting method behaviour
+# and adds fallback gem call removed in https://github.com/rails/rails/commit/4c3725723f15fab0a424cb1318b82b460714b72f
+require File.join(File.dirname(__FILE__), '../lib/old_rubygems_patch')
+
 
 Rails::Initializer.run do |config|
   # Load intial mySociety config
diff --git a/lib/old_rubygems_patch.rb b/lib/old_rubygems_patch.rb
new file mode 100644
index 000000000..5601a5e90
--- /dev/null
+++ b/lib/old_rubygems_patch.rb
@@ -0,0 +1,42 @@
+require File.join(File.dirname(__FILE__),'..','vendor','rails','railties','lib','rails','gem_dependency.rb')
+
+module Rails
+  class GemDependency < Gem::Dependency
+  
+    # This definition of the requirement method is a patch
+    if !method_defined?(:requirement)
+      def requirement
+        req = version_requirements
+      end
+    end
+  
+    def add_load_paths
+      self.class.add_frozen_gem_path
+      return if @loaded || @load_paths_added
+      if framework_gem?
+        @load_paths_added = @loaded = @frozen = true
+        return
+      end
+
+      begin
+        dep = Gem::Dependency.new(name, requirement)
+        spec = Gem.source_index.find { |_,s| s.satisfies_requirement?(dep) }.last
+        spec.activate           # a way that exists
+      rescue
+        begin 
+          gem self.name, self.requirement # <  1.8 unhappy way
+        # This second rescue is a patch - fall back to passing Rails::GemDependency to gem
+        # for older rubygems
+        rescue ArgumentError
+          gem self
+        end
+      end
+
+      @spec = Gem.loaded_specs[name]
+      @frozen = @spec.loaded_from.include?(self.class.unpacked_path) if @spec
+      @load_paths_added = true
+    rescue Gem::LoadError
+    end
+  end
+  
+end