修改Bug，提交代码。

Signed-off-by: zouap <zouap@pcl.ac.cn>

routers/repo/ai_model_convert.go

@@ -550,6 +550,9 @@ func ShowModelConvertInfo(ctx *context.Context) {
 
 	job, err := models.QueryModelConvertById(ctx.Query("ID"))
 	if err == nil {
+		if job.TrainJobDuration == "" {
+			job.TrainJobDuration = "00:00:00"
+		}
 		ctx.Data["task"] = job
 	} else {
 		ctx.ServerError("Not found task.", err)