certificate problem for *.github.com

Hello Git community! Here is my question: until a few days ago I used to be able to point to a certain file in my git repository with the following url: http://github.com/percolator/percolator/raw/xml-1-1/src/xml/percolator_in.xsd Now this gets redirected to an https address. No problem opening it with the browser; but I do get an error with, for instance, wget (...and, more important, with a program that attempts to use that file as a schema against which some xml code is validated...) I get: certificate common name `*.github.com' doesn't match requested host name `github.com'

wget --no-check-certificate works...

Thank you! Mattia