Adding this in `dev-cmd/ruby.rb` allows us to suppress warnings like:
```
/home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/language/python.rb:8: warning: Insecure world writable dir /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/scm in PATH, mode 040777
```