I got a surprise this morning (June 8) when updating Homebrew:

$ brew update
Updated Homebrew from b9552a5 to b2c9625.
Updated 4 taps (caskroom/cask, caskroom/fonts, homebrew/core, homebrew/dupes).
==> Cleaning up /Library/Caches/Homebrew...
==> Migrating /Library/Caches/Homebrew to /Users/me/Library/Caches/Homebrew...
==> Deleting /Library/Caches/Homebrew...

Seems weird to move the cache to your home folder, when the default for the package manager itself is still /usr/local/bin. I suppose at some level this means one could run multiple Homebrews on the same machine without caches clashing.

Caches Clashing. HARRISON FORD. “I’m going to clash your cache!"

It also looks like the Cask caskroom has moved as well:

$ brew cask update
==> Warning: The default Caskroom location has moved to /usr/local/Caskroom.
==> Please migrate your Casks to the new location, or if you would like to 
==> keep your Caskroom at /opt/homebrew-cask/Caskroom, add the following to 
==>     --caskroom=/opt/homebrew-cask/Caskroom
==> For more details on each of those options, see 
==> https://github.com/caskroom/homebrew-cask/issues/21913.

Fortunately, this hasn’t moved:

$ apt-get update
==> Ruben you eejit, you're on your Mac.
$ pkg update
==> Ruben you eejit, you're on your Mac.

Cue a reference to the Universal Install Script, which regrettably uses bash and is therefore less portable than it first suggests. Shocking, I know.