init: expand destination url as a configured paths
Most commands expands configured paths when repositories are specified, just as
the urls help says. Clone also expands the destination path. Clone is morally
equivalent to init + push/pull, so init should also expand the destination path
- and that is what this patch makes it do.
There is no really good usecases for this and in most cases it doesn't matter,
but consistency is nice, and otherwise we would have to document the exception.