Previews that are built in GHA runners show random commit hashes

[egeakman]

Latest Read the Docs build for #1101:

Latest static server preview build for the same PR:

It is not cache:

I tried to track down the commit that it's showing but it doesn't exist at least in their respective branches.

The content is new though, only the commit hash is wrong.

[egeakman]

cc @artcz

[artcz]

hmm.. best I can guess right now, it's probably using the detached build commit from the GHA environment. I guess passing the commit hash explicitly (same way we pass the branch name) should solve it.