Auto merge of #3717 - king6cong:clean, r=alexcrichton
Auto merge of #3717 - king6cong:clean, r=alexcrichton

remove unnecessary code

tsurai/cargo,achanda/cargo,nipunn1313/cargo,rustyhorde/cargo,eminence/cargo,vojtechkral/cargo,rustyhorde/cargo,rustyhorde/cargo,eminence/cargo,achanda/cargo,nipunn1313/cargo,vojtechkral/cargo,tshepang/cargo,eminence/cargo,durka/cargo,rust-lang/cargo,tshepang/cargo,tsurai/cargo,achanda/cargo,rust-lang/cargo,achanda/cargo,tshepang/cargo,tshepang/cargo,rust-lang/cargo,tsurai/cargo,vojtechkral/cargo,nipunn1313/cargo,rust-lang/cargo,tsurai/cargo,nipunn1313/cargo,vojtechkral/cargo,tsurai/cargo,durka/cargo,rustyhorde/cargo,eminence/cargo,durka/cargo,durka/cargo