Fixing json decode error on druiddatasourcemodelview/api/read (#4291)
Fixing json decode error on druiddatasourcemodelview/api/read (#4291)


timifasubaa/incubator-superset,apache/incubator-superset,airbnb/superset,zhouyao1994/incubator-superset,timifasubaa/incubator-superset,dmigo/incubator-superset,mistercrunch/panoramix,timifasubaa/incubator-superset,airbnb/superset,dmigo/incubator-superset,airbnb/caravel,timifasubaa/incubator-superset,airbnb/caravel,zhouyao1994/incubator-superset,zhouyao1994/incubator-superset,zhouyao1994/incubator-superset,mistercrunch/panoramix,apache/incubator-superset,apache/incubator-superset,mistercrunch/panoramix,airbnb/superset,dmigo/incubator-superset,apache/incubator-superset,airbnb/superset,apache/incubator-superset,airbnb/caravel,zhouyao1994/incubator-superset,dmigo/incubator-superset,mistercrunch/panoramix,airbnb/caravel