add default option on head requests

lib/httparty.rb

@@ -268,7 +268,9 @@ module HTTParty
     end
 
     # Declare that you wish to maintain the chosen HTTP method across redirects.
-    # The default behavior is to follow redirects via the GET method.
+    # The default behavior is to follow redirects via the GET method, except
+    # if you are making a HEAD request, in which case the default is to
+    # follow all redirects with HEAD requests.
     # If you wish to maintain the original method, you can set this option to true.
     #
     # @example
@@ -517,6 +519,9 @@ module HTTParty
 
     # Perform a HEAD request to a path
     def head(path, options = {}, &block)
+      unless options.has_key?(:maintain_method_across_redirects)
+        options[:maintain_method_across_redirects] = true
+      end
       perform_request Net::HTTP::Head, path, options, &block
     end
 

spec/httparty_spec.rb

@@ -588,6 +588,24 @@ RSpec.describe HTTParty do
     end
   end
 
+  describe "head requests should follow redirects requesting HEAD only" do
+    before do
+      @request = HTTParty::Request.new(Net::HTTP::Head, 'http://api.foo.com/v1')
+      @redirect = stub_response 'first redirect', 302
+      @redirect['location'] = 'http://foo.com/bar'
+      allow(HTTParty::Request).to receive_messages(new: @request)
+    end
+
+    it "should set maintain_method_across_redirects option if unspecified" do
+      # This is what I'm trying to do:
+      # expect(@klass.head('/foo').body).to be_nil
+
+      # This is what I get instead:
+      # HTTParty::RedirectionTooDeep: HTTP redirects too deep
+      # from /Users/Lehman/Desktop/Code/httparty/lib/httparty/request.rb:344:in `validate'
+    end
+  end
+
   describe "with multiple class definitions" do
     before(:each) do
       @klass.instance_eval do