datalad-annex supports cloning from the web special remote,
using an url that contains the result of pushing to eg, a directory
special remote.

`datalad-annex::https://example.com?type=web&url={noquery}`

Supporting something like this in git-remote-annex would be good.

The httpalso special remote already exists to handle this kind of thing.

In fact, it just works with git-remote-annex!

Eg, this url on my laptop is a directory special remote
accessed via the web server:

    annex::13c2500f-a302-4331-9720-6ec43cb8da2b?encryption=none&exporttree=yes&type=httpalso&url=http%3A%2F%2Flocalhost%2F~joey%2Ftmp%2Fd

But, while fetching from a httpalso special remote works, and cloning
works, after cloning, fetching again fails:

    joey@darkstar:~/tmp/newp2>git fetch origin
    git-annex: no url configured for httpalso special remote

> fixed that, [[done]] --[[Joey]]
