I've seen several reports of people who have bare hostnames (e.g. `keys.example.net`) for `keyserver` in their configurations for either `dirmngr.conf` or `gpg.conf` (or in scripts, etc).
The current implementation appears to demand a full URI, failing on a bare hostname with:
```
0 dkg@alice:~$ gpg --recv $PGPID
gpg: keyserver receive failed: Syntax error in URI
2 dkg@alice:~$
```
If a bare hostname is present, dirmngr should first try it with an `hkps://` prefix, and fall back to an `hkp://` prefix if hkps is not available. It should probably also emit a warning that it is doing this rewriting, which the user can avoid by explicitly specifying the full URI in `dirmngr.conf`.
As an easier/simpler fix, we could not do the `hkp://` fallback, and that would still be an improvement over the status quo.