Merge pull request #2124 from arunagw/render_partial_invalid_check_fix

Checking with to_s. As regexp fail with 1.8.7

actionpack/lib/action_view/renderer/partial_renderer.rb

@@ -300,8 +300,7 @@ def setup(context, options, block)
       else
         paths.map! { |path| retrieve_variable(path).unshift(path) }
       end
-
-      if String === partial && @variable !~ /^[a-z_][a-zA-Z_0-9]*$/
+      if String === partial && @variable.to_s !~ /^[a-z_][a-zA-Z_0-9]*$/
         raise ArgumentError.new("The partial name (#{partial}) is not a valid Ruby identifier; " +
                                 "make sure your partial name starts with a letter or underscore, " +
                                 "and is followed by any combinations of letters, numbers, or underscores.")