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)
- Run `brew search` for local formulae first (as it's quickest) rather
than checking Git history.
- Don't output `Searching taps...` because `Searching taps on GitHub...`
is output by the called function (and because it'll say it's searching
taps even when it is not if `HOMEBREW_NO_GITHUB_API` is set).
GitHub has requested we request our usage of shallow clones. As a
result:
- do default to shallow clones on CI
- do not do --shallow-since when setting up new repositories in
`brew update`
- do not support shallow clones of homebrew-core at all
We may consider in future unshallowing all clones unconditionally.
The refactor in 6e8f5d0958247e4b4d629866099ed2836a0e0863 means that the
exception no longer exposes the name of the package with multiple versions,
and as a result the rescuer is unable to print this information.
Because we now have a path in which MultipleVersionsInstalledError doesn't
have the name at all, we can't reasonably restore the old behaviour.
And since rack resolution happens purely internal to the function that
raises the exception, the caller has no way to know what name to use.
However, since the exception text gets printed anyway, we can just move
this text into the exception itself.
Fixes the following error:
```
Error: mpd has multiple installed versions
Error: undefined method `name' for #<MultipleVersionsInstalledError:0x00007fc6009d8870>
/usr/local/Homebrew/Library/Homebrew/cmd/uninstall.rb:137:in `rescue in uninstall'
/usr/local/Homebrew/Library/Homebrew/cmd/uninstall.rb:135:in `uninstall'
/usr/local/Homebrew/Library/Homebrew/brew.rb:119:in `<main>'
```
