Thanks Randy. It was my CodeMirror submodule that is not up-to-date version. So the second point is not true. 

@TomMalbran -- Thanks for setting it to false. Even though my second point is not true, auto close brackets can be annoying for most uses who are updating the existing code. Consider when you want to wrap something with quotes or parenthesis and you set the cursor before a word and type the opening paren or quote, this CM plugin will auto insert the closing one, which shouldn't be in this case.