mock improvements

[BJ Dierkes]

>
>> 1) more reliable mount/umount
>>   several people have pointed out instances where mock exits leaving
>>   mounts behind (specifically /dev), and the next invokation of mock
>>   ends up 'rm -rf' the host machine's /dev. Bad....
>
> And /dev/pts and /proc.
>

Yes...  this is one should be pushed way up in priority if  
possible...  building any apps around mock will lead to many a  
developer wondering what just happened to their '/dev'...  as is the  
case right now for me.... atleast 10 times in the last few hours.

Thanks.