In Django, when I use:
{{ request.build_absolute_uri }}{% static \"img/myimage.jpg\" %}
It produces: \'http://myurl.com//static/img/myimage
build_absolute_uri
takes the location as an argument which handles the double slash problem.
Unfortunately you cannot pass arguments via the django template language.
You will need to build a custom template tag or filter which accepts an argument to the build_absolute_uri
function.
One of the many reasons I prefer Jinja as I can just do this:
{{ request.build_absolute_uri(static('img/foo.png')) }}