Commandline curl -I flag fails ("HTTP/1.1 405 Method Not Allowed") on all our python-generated URLs.

http://curl.haxx.se/docs/manpage.html

-i, --include

(HTTP) Include the HTTP-header in the output. The HTTP-header includes things like server-name, date of the document, HTTP-version and more...

-I, --head

(HTTP/FTP/FILE) Fetch the HTTP-header only! HTTP-servers feature the command HEAD which this uses to get nothing but the header of a document. When used on an FTP or FILE file, curl displays the file size and last modification time only.

Appengine automatically responds to HTTP HEAD for static URLs e.g. most of docs/* but for python scripted content we need to implement a head function, see https://cloud.google.com/appengine/docs/python/tools/webapp/requesthandlerclass#RequestHandler_head for details.

See the corresponding 'get' function for details, https://github.com/schemaorg/schemaorg/blob/master/api.py#L865

It is not a huge task but needs some care to deal with the content negotiation (HTML vs JSON-LD) of the homepage.