Use temp_file instead of broken manual code

lib/pry/default_commands/introspection.rb

@@ -145,22 +145,19 @@ class Pry
                       _pry_.input_array.reverse_each.find{ |x| x && x.strip != "" } # No present? in 1.8
                     end || ""
 
-          file_name = temp_file do |f|
-            f.puts(content)
-          end
           line = content.lines.count
 
-          invoke_editor(file_name, line)
-
-          if !opts.n?
-            silence_warnings do
-              eval_string.replace(File.read(file_name))
+          temp_file do |f|
+            f.puts(content)
+            f.flush
+            invoke_editor(f.path, line)
+            if !opts.n?
+              silence_warnings do
+                eval_string.replace(File.read(f.path))
+              end
             end
           end
 
-          # don't leak temporary files
-          File.unlink(file_name)
-
         # edit of remote code, eval'd at top-level
         else
           if opts.ex?

test/test_default_commands/test_introspection.rb

@@ -143,11 +143,6 @@ describe "Pry::DefaultCommands::Introspection" do
         @line.should == 2
       end
 
-      it "should delete the temporary file" do
-        mock_pry("edit")
-        File.exist?(@file).should == false
-      end
-
       it "should evaluate the expression" do
         Pry.config.editor = lambda {|file, line|
           File.open(file, 'w'){|f| f << "'FOO'\n" }