convert: Use clone's behaviour for the default destionation name. Adjusted the documentation for this and for the fact that the destionation is created even if a name is specified.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg rollback
hg verify
hg parents
hg status