Use package transformation to get commit of eglot

[jgart]

Hi,

Is anyone able to successfully get the latest eglot with a package 
transformation?

I get the following error for commit 000b7fdce93ed29c505a7fa75baaf87094fd690a:

```
$ guix install emacs-eglot 
--with-commit=emacs-eglot=000b7fdce93ed29c505a7fa75baaf87094fd690a
guix install: error: the source of emacs-eglot@1.8 is not a Git reference
```

am i doing it all wrong?