module Roda::RodaPlugins::Head::RequestMethods

def is_get?

Consider HEAD requests as GET requests. 
def is_get?
  super || head?
end

def match_method(method)

the given methods is a GET request.
If the current request is a HEAD request, match if one of 
def match_method(method)
  super || (!method.is_a?(Array) && head? && method.to_s.upcase == 'GET')
end

def method_not_allowed(verbs)

of the Allow header options, then HEAD is as well.
Work with the not_allowed plugin so that if GET is one 
def method_not_allowed(verbs)
  verbs = verbs.sub('GET', 'HEAD, GET')
  super
end