Fix a variable type for building on Travis.
Fix a variable type for building on Travis.

vittvolt/peloton,cmu-db/peloton,eric-haibin-lin/peloton-1,cmu-db/peloton,eric-haibin-lin/peloton-1,jessesleeping/iso_peloton,eric-haibin-lin/peloton-1,vittvolt/15721-peloton,apavlo/peloton,haojin2/peloton,cmu-db/peloton,vittvolt/15721-peloton,prashasthip/peloton,apavlo/peloton,AngLi-Leon/peloton,phisiart/peloton-p3,vittvolt/15721-peloton,AllisonWang/peloton,haojin2/peloton,malin1993ml/peloton,eric-haibin-lin/peloton-1,prashasthip/peloton,yingjunwu/peloton,haojin2/peloton,AngLi-Leon/peloton,prashasthip/peloton,PauloAmora/peloton,jessesleeping/iso_peloton,seojungmin/peloton,PauloAmora/peloton,wangziqi2016/peloton,yingjunwu/peloton,phisiart/peloton-p3,malin1993ml/peloton,haojin2/peloton,yingjunwu/peloton,jessesleeping/iso_peloton,AllisonWang/peloton,ShuxinLin/peloton,apavlo/peloton,prashasthip/peloton,haojin2/peloton,wangziqi2016/peloton,wangziqi2016/peloton,wangziqi2016/peloton,seojungmin/peloton,wangziqi2016/peloton,prashasthip/peloton,cmu-db/peloton,haojin2/peloton,jessesleeping/iso_peloton,vittvolt/15721-peloton,yingjunwu/peloton,cmu-db/peloton,cmu-db/peloton,AngLi-Leon/peloton,vittvolt/peloton,yingjunwu/peloton,ShuxinLin/peloton,ShuxinLin/peloton,AngLi-Leon/peloton,seojungmin/peloton,malin1993ml/peloton,AngLi-Leon/peloton,seojungmin/peloton,ShuxinLin/peloton,malin1993ml/peloton,ShuxinLin/peloton,AllisonWang/peloton,AllisonWang/peloton,vittvolt/15721-peloton,AllisonWang/peloton,apavlo/peloton,seojungmin/peloton,vittvolt/15721-peloton,wangziqi2016/peloton,phisiart/peloton-p3,phisiart/peloton-p3,malin1993ml/peloton,ShuxinLin/peloton,vittvolt/peloton,malin1993ml/peloton,PauloAmora/peloton,jessesleeping/iso_peloton,phisiart/peloton-p3,eric-haibin-lin/peloton-1,prashasthip/peloton,phisiart/peloton-p3,vittvolt/peloton,apavlo/peloton,eric-haibin-lin/peloton-1,PauloAmora/peloton,PauloAmora/peloton,seojungmin/peloton,AngLi-Leon/peloton,jessesleeping/iso_peloton,apavlo/peloton,PauloAmora/peloton,yingjunwu/peloton,vittvolt/peloton,vittvolt/peloton,AllisonWang/peloton,jessesleeping/iso_peloton