For cleaner upgrade, have Homebrew .munki recipe delete old Homebrew subdirs first

[aysiu]

To avoid an install loop. More details in #102

[aysiu]

Actually, I think the fix has to be slightly more complicated than what I've proposed here. If you blow out the entire /opt/homebrew dir, that actually deletes all the homebrew-installed stuff as well. Will have to look into this more...

[aysiu]

Very odd. I don't see why it wouldn't update. The package seems to deliver the new payload, which should overwrite the old payload. The postinstall script in the package does seem cleanup, but it shouldn't prevent the version reported from updating...

[aysiu]

Filed an issue with brew: Homebrew/brew#19287

[nstrauss]

@aysiu Played around with this and think I have a solution. The Homebrew installer and supporting commands are heavily entrenched in git. Best I can tell /opt/.git and /opt/homebrew/Library/Homebrew aren't being updated by the package as they should be. If it were done with brew upgrade I assume the version would be updated accurately. Definitely a bug. Thanks for opening the issue. Workaround for now...

#!/bin/zsh

if [[ $(uname -m) == "x86_64" ]]; then
  brew_dir="/usr/local/Homebrew"
else
  brew_dir="/opt/homebrew"
fi

if [[ -d "$brew_dir" ]]; then
  /bin/rm -rf "$brew_dir/.git"
  /bin/rm -rf "$brew_dir/Library/Homebrew"
fi

If I only remove .git and install the latest package, brew --version is correct but I get the error...

Warning: You have uncommitted modifications to Homebrew/brew.
If this is a surprise to you, then you should stash these modifications.
Stashing returns Homebrew to a pristine state but can be undone
should you later need to do so for some reason.
  cd /opt/homebrew && git stash -u && git clean -d -f

Uncommitted files:
  ?? Library/Homebrew/test/support/fixtures/bottles/testball_bottle-0.1.aarch64_linux.bottle.tar.gz

Which clued me into the diff at $brew_dir/Library/Homebrew being location of Homebrew's own formula. Delete both and brew chugs on happy as ever. Please test yourself and see if it works as I described. If so, append the PR and I'll merge. Thanks.

[aysiu]

Great find, @nstrauss !

Yean, that tracks with my testing:

> sudo installer -pkg ~/Downloads/Homebrew-4.4.17.pkg -target /
installer: Package name is Homebrew
installer: Upgrading at base path /
installer: The upgrade was successful.

> /opt/homebrew/bin/brew --version
Homebrew 4.4.17

> sudo /bin/rm -rf /opt/homebrew/.git

> sudo /bin/rm -rf /opt/homebrew/Library/Homebrew 

> sudo installer -pkg ~/Downloads/Homebrew-4.4.20.pkg -target /
installer: Package name is Homebrew
installer: Upgrading at base path /
installer: The upgrade was successful.

> /opt/homebrew/bin/brew --version            
Homebrew 4.4.20

[aysiu]

@nstrauss I think this commit should do it. Let me know what you think.