Fix bug where we ignored type passed into Pry::Code.from_file

lib/pry/code.rb

@@ -41,7 +41,7 @@ class Pry
         else
           if File.readable?(fn)
             f = File.open(fn, 'r')
-            code_type = type_from_filename(fn)
+            code_type ||= type_from_filename(fn)
           else
             raise MethodSource::SourceNotFoundError, "Cannot open #{fn.inspect} for reading."
           end

test/test_code.rb

@@ -23,6 +23,12 @@ describe Pry::Code do
       end
     end
 
+    should 'use the provided extension' do
+      temp_file('.c') do |f|
+        Pry::Code.from_file(f.path, :ruby).code_type.should == :ruby
+      end
+    end
+
     should 'raise an error if the file doesn\'t exist' do
       proc do
         Pry::Code.from_file('/knalkjsdnalsd/alkjdlkq')