Brew won't uninstall a package because it can't find another formula I'm trying to get rid of the php56-pdo-pgsql formula installed by Brew so that I can install it again with the --without-homebrew-php option. pgsql is installed in the copy of PHP that came with OS X 10.12. However when I try to uninstall it like this

brew uninstall php56-pdo-pgsql


brew complains like this

Error: No available formula with the name "mashape/kong/luajit"
First steps would be to brew update (twice) then brew doctor to make sure all is good in brew. Then check that the XCode command line tools and Xcode itself are up to date.

If, after that, you still get the problem you may have found a formula bug so file an issue at https://github.com/Homebrew/brew