Homebrew now has eg:

datalads-imac:~ joey$ ls -l /Users/joey/homebrew/Cellar/git/2.23.0/libexec/git-core
total 36776
lrwxr-xr-x   1 joey  staff       13 Aug 29 13:38 git -> ../../bin/git
lrwxr-xr-x   1 joey  staff       13 Aug 29 13:38 git-add -> ../../bin/git

So the target of the symlink also needs to be installed now.

Doing it in shell code was too hairy for my dentistry-addled brain, so
reimplemented in haskell. Also using it for building linuxstandalone.