Potential upgrade script improvments

[YesThatAllen]

Problem
The upgrade script can be brittle at times, but is generally fine.

This issue is a place where we can recap older or known issues, and potentially make improvements.

Enhancement

• I'd like to see the script able to run from any folder.
  • that could mean running git with git --git-dir=__ --work-tree=___
• It shouldn't be too hard to be able to run the existing git script, vs pulling down the new version.
• it'd be nice not to hard code the repo's git urls

Additional context

I don't know that there's anything we NEED to do yet, but an issue like this can be good for gathering notes until it's decided an improvement is desired.