Re: t5000-tar-tree.sh failing

> Several other test frameworks provide a "skip" method to indicate why  
> we've skipped something.  We could do something similar...
> 
> if skip 'unzip -h' 'tests need unzip'; then
>    # unzip tests
> fi
> 
> skip() {
>   # Have not checked to see if this is anything resembling working code
>   if eval $1 > /dev/null 2>&1; then
>     true
>   else
>     echo "* skipping tests: $2" 1>&2
>     false
>   fi
> }
> 
> Mostly so that skipped tests are obvious, provide a reason, and have  
> a standardized display format.  Again, too busy in actual work to try  
> to do this myself right now, but might hack at it this afternoon if  
> nobody else (hopefully someone more fluent in shell than I am) does.