add slash back to disk check

Author: danawillow

google/resource_compute_instance_test.go

@@ -813,7 +813,7 @@ func testAccCheckComputeInstanceDisk(instance *compute.Instance, source string,
 		}
 
 		for _, disk := range instance.Disks {
-			if strings.HasSuffix(disk.Source, source) && disk.AutoDelete == delete && disk.Boot == boot {
+			if strings.HasSuffix(disk.Source, "/"+source) && disk.AutoDelete == delete && disk.Boot == boot {
 				return nil
 			}
 		}