RFC: always git shallow clone

[anmonteiro]

• In Shallow clone github sources #1089, @ManasJayanth mentioned you can only shallow clone long hashes because otherwise you can't call rev-parse.
• However, the Git.revParse function isn't used anywhere throughout the codebase.

This proposal lifts the restriction that you can only shallow clone long hashes. I'm not aware of all the implications, though, so I appreciate folks chiming in if this is a no-go.

[anmonteiro]

I just ran the github slow test locally, and it worked 👍

[EduardoRFS]

I also think this is reasonable. If we hit a problem we can revert it.

[ManasJayanth]

I want to take another at it this weekend

[EduardoRFS]

@ManasJayanth I think we can merge this as soon as the CI is green

[ManasJayanth]

revParse can be removed safely (but I don't think we gain much by doing so)

The if block needs to stay

git clone https://github.com/esy/esy --depth 1
cd esy
git fetch https://github.com/esy/esy 802803c0 # fails
git fetch https://github.com/esy/esy 802803c00ea244536b6b4ceab7a14a75dd16b1d5 # succeeds

I think my revParse comment was unrelated to the codebase - sorry cant remember!

Not sure why the e2e didn't fail. Needs to be looked into.