This post is now obsolete: Fixed in upstream

The default Linuxbrew-installed newt library has a bug that prevents it from finding the path of installed Python versions. This will prevent byobu-config from opening due to missing snack module. The solution is simple: replace the hard-coded search path in configure.

Solution

Run brew edit newt.

# PATCH BEGIN
    if OS.linux?
      inreplace "configure", "/usr/include/python", "#{HOMEBREW_PREFIX}/include/python"
    end
# PATCH END
    system "./configure", *args
    system "make", "install"

Modified formula: https://github.com/ProfFan/homebrew-core/blob/master/Formula/newt.rb