Thanks nijel for the patch.
You cannot change the usage from 'fs' to 'dfs'. Though it looks to be changed, since we are calling FsShell by invoking 'hdfs dfs' from HDFS perspective, But FSShell is generic and any other FileSystem can use this shell. Other file systems will call this by 'hadoop fs'. Actual FileSystem referred inside depends on the 'fs.defaultFS' configuration or "-fs" argument from the client side.
So you might need to keep the usage as previous. And update the new test accordingly. Also another test failure fix may not be necessary after revert of usage.