Remapping hostname prevents using `gh stack submit`

[jeff-younker]

I use a synthetic hostname mapping in ~/.gitconfig (1) in conjunction with my .ssh/config (2) to select the SSH host key and user identity. In this case, the synthetic hostname is fastalyze.github.com. When I run gh stack submit this happens:

gh stack submit
Checking stack state...
✗ failed to create GitHub client: determining repository: unable to determine current repository, none of the git remotes configured for this repository point to a known GitHub host

I suspect there is a check for stacked PR support based on the hostname, and it's not recognizing fastalyze.github.com.

(1) ~/.gitconfig stanza:

[url "git@fastalyze.github.com:fastalyze/"]
    insteadOf = git@github.com:fastalyze/

[url "git@fastalyze.github.com:fastalyze/"]
        insteadOf = https://github.com/fastalyze/

(2) .ssh/config stanza:

host fastalyze.github.com
    Hostname github.com
    User "jeff-younker"
    IdentityFile ~/.ssh/id_fastalyze
    IdentityAgent none