Fixbug: task name

tasks/index.wdl

@@ -15,6 +15,6 @@ task index {
 		dataDisk: "cloud_ssd " + disk_size + " /cromwell_root/"
 	}
 	output {
-		File bai = "${bam}.bai"
+		File bai = "${basename bam}.bai"
 	}
 }