Allow "clone" uri in mirror target uri
### Problem to solve
It would be nice when URIs copied from "clone" could be used directly as a push target. E.g. when trying to use the uri from

gitlab rejects this with

<!--- What problem do we solve? -->
and I have to rewrite it manually (prepend `ssh:` and replace second `:` with `/`)
### Proposal
Rewrite such URIs automatically or accept them as-is.
issue