expression: make golint happy (#3872)
expression: make golint happy (#3872)


zimulala/tidb,spongedu/tidb,kyle-wang/tidb,pingcap/tidb,c4pt0r/tidb,kyle-wang/tidb,gaocegege/tidb,pingcap/tidb,CodeRushing/tidb,cosmtrek/tidb,c4pt0r/tidb,spongedu/tidb,8cbx/tidb,qiuyesuifeng/tidb,Cofyc/tidb,kyle-wang/tidb,pingcap/tidb,louishust/tidb,XuHuaiyu/tidb,XuHuaiyu/tidb,ngaut/tidb,qiuyesuifeng/tidb,yuanwhy/tidb,louishust/tidb,c4pt0r/tidb,EvilMcJerkface/tidb,wusphinx/tidb,gaocegege/tidb,ngaut/tidb,kyle-wang/tidb,kyle-wang/tidb,cosmtrek/tidb,EvilMcJerkface/tidb,Cofyc/tidb,c4pt0r/tidb,tiancaiamao/tidb,zimulala/tidb,8cbx/tidb,coocood/tidb,yuanwhy/tidb,yangwenmai/tidb,ngaut/tidb,ngaut/tidb,ngaut/tidb,yangwenmai/tidb,pingcap/tidb,mccxj/tidb,CodeRushing/tidb,kyle-wang/tidb,ming-relax/tidb,ming-relax/tidb,tiancaiamao/tidb,Nify/tidb,Nify/tidb,wusphinx/tidb,pingcap/tidb,c4pt0r/tidb,pingcap/tidb,coocood/tidb,c4pt0r/tidb,ngaut/tidb,mccxj/tidb