def bad_shebang?
    return false if binary?

    shebang.match?(/^#!\s*\/usr\/bin\/env\s*ruby(\d.*)$/) # https://rubular.com/r/ozbNEPVInc3sSN
  end
Returns false if the shebang line has a ruby binary
that is not simply "ruby" or "ruby.exe"

Example:

bin_dir = Pathname.new(Dir.pwd).join("bin")
binstub = BinstubWrapper.new(bin_dir.join("rails_good"))
binstub.shebang # => "#!/usr/bin/env ruby\n"
binstub.bad_shebang? # => false

binstub = BinstubWrapper.new(bin_dir.join("rails_bad"))
binstub.shebang # => "#!/usr/bin/env ruby2.5\n"
binstub.bad_shebang? # => true