>>> Would it not be easier to unconditionally untar the contents in a 
>>> temporary directory, and to either move its contents to the current 
>>> directory if it contains only one entry, or to rename it to a 
>>> directory based on the tar file name when it contains more than one 
>>> entry?
>> 
>> Easier in what sense?
>
> In the sense of "DWIM".
>

Patch attached.