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
# a test for issue586
hg init a
cd a
echo a > a
hg ci -Ama
hg init ../b
cd ../b
echo b > b
hg ci -Amb
hg pull -f ../a
hg merge
hg rm -f a
hg ci -Amc
hg st -A