clone: simplifying dest repo creation since creating a repo raises an exception if the repo already exists, there's no need to try to create one. add some test for repo creation when the destination exists

#!/bin/sh

echo "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH

hg init a
cd a

echo 'base' > base
hg ci -Ambase -d '1 0'

hg qnew -mmqbase mqbase

hg qsave
hg qrestore 2