Summary: See PHI1030. When installs hit this error, provide more details about which node we ended up on and what's going on.

Test Plan:
```
$ git pull
phabricator-ssh-exec: This repository request (for repository "spellbook") has been incorrectly routed to a cluster host (with device name "local.phacility.net", and hostname "orbital-3.local") which can not serve the request.

The Almanac device address for the correct device may improperly point at this host, or the "device.id" configuration file on this host may be incorrect.

Requests routed within the cluster by Phabricator are always expected to be sent to a node which can serve the request. To prevent loops, this request will not be proxied again.

(This is a read request.)
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
```

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20002