allow query.conditions to be called multiple times without losing conditions

lib/cancan/query.rb

@@ -26,10 +26,10 @@ module CanCan
     def conditions
       if @rules.size == 1 && @rules.first.base_behavior
         # Return the conditions directly if there's just one definition
-        @rules.first.tableized_conditions
+        @rules.first.tableized_conditions.dup
       else
         @rules.reverse.inject(false_sql) do |sql, rule|
-          merge_conditions(sql, rule.tableized_conditions, rule.base_behavior)
+          merge_conditions(sql, rule.tableized_conditions.dup, rule.base_behavior)
         end
       end
     end

spec/cancan/query_spec.rb

@@ -104,4 +104,13 @@ describe CanCan::Query do
     @ability.can :read, Project, :project => { :foo => {:bar => true}, :bar => {:zip => :zap} }
     @ability.query(:read, Project).joins.inspect.should orderlessly_match([{:project => [:bar, :foo]}, {:company => [:bar]}].inspect)
   end
+
+  it "should not forget conditions when calling with SQL string" do
+    @ability.can :read, Project, :foo => 1
+    @ability.can :read, Project, ['bar = ?', 1]
+    query = @ability.query(:read, Project)
+    2.times do
+      query.conditions.should == "(bar = 1) OR (foo=1)"
+    end
+  end
 end