The way we currently handle @-versioned formulae linking is pretty
labourius:
- it requires extensive use of `link_overwrite` to avoid the `link`
stage failing on certain install/upgrade scenarios
- we teach people to use `brew link --force` whenever they wish to
link a versioned formulae when it's pretty obvious what's expected
in that situation
Instead, let's:
- automatically unlink other versioned formulae when linking a
versioned formula (either through `brew link` or `install`/`upgrade`
/`reinstall`)
- notify the user what we've done (with the same messaging as if
they had run `brew link` manually)
Everything that used HOMEBREW_CELLAR/canonical_name
could point to something that doesn't exist because
loader_for tries to load new name formula if no old
name found. However there can be software installed
from path with the same name that renamed formulae
had and we still need to link/unlink/uninstall etc
that software. The solution is Formulary#to_rack
method that returns rack for given name.
- Add Formulary#to_rack
- Update ARGV.kegs
- Update cmd/switch
