Fix missing constant in test.
Fix missing constant in test.

mcuadros/mgo,deafgoat/mgo,raymondjacobson/mgo,go-mgo/travis-test,mjs/mgo,tchajed/mgo,raymondjacobson/mgo,deafgoat/mgo,mjs/mgo,jjz/mgo,tchajed/mgo,go-mgo/travis-test,lucasjo/mgo,lucasjo/mgo,tchajed/mgo,tobyzxj/mgo,tobyzxj/mgo,velocity-toolkit/mgo,mcuadros/mgo,jjz/mgo,Yottaa/mgo.v2,tmc/mgo,mcuadros/mgo,mcuadros/mgo,jackspirou/mgo,gabrielrussell/mgo,raymondjacobson/mgo,velocity-toolkit/mgo,DroiTaipei/mgo,Danzeer/mgo,dmage/mgo,jackspirou/mgo,deafgoat/mgo,Yottaa/mgo.v2,SocialExplorerFork/mgo,velocity-toolkit/mgo,velocity-toolkit/mgo,jjz/mgo,tobyzxj/mgo,Yottaa/mgo.v2,DroiTaipei/mgo,deafgoat/mgo,henrylee2cn/mgo,SocialExplorerFork/mgo,henrylee2cn/mgo,tchajed/mgo,Danzeer/mgo,hexadecy/mgo,gabrielrussell/mgo,DroiTaipei/mgo,SocialExplorerFork/mgo,tmc/mgo,lucasjo/mgo,dmage/mgo,hexadecy/mgo,Danzeer/mgo,mjs/mgo,tobyzxj/mgo,hexadecy/mgo,tmc/mgo,Yottaa/mgo.v2,dmage/mgo,tchajed/mgo,gabrielrussell/mgo,jjz/mgo,jackspirou/mgo,lucasjo/mgo,jackspirou/mgo,go-mgo/travis-test,go-mgo/travis-test,hexadecy/mgo,tmc/mgo,raymondjacobson/mgo,gabrielrussell/mgo,mjs/mgo,henrylee2cn/mgo,DroiTaipei/mgo,henrylee2cn/mgo,SocialExplorerFork/mgo,dmage/mgo,roamz/mgo,Danzeer/mgo