Add file link does not respect chosen branch

[myahl]

The link uses "master" for the branch. We do not have a master branch, so for us it gives a 404 page. If I manually change the URL to an existing branch, it works fine.

github.com/myOrganization/myRepo/new/master?filename=.github%2Fdeploy.yml&value=%23%20View%20examples%20and%20documentation%20at%20https%3A%2F%2Fdeliverybot.dev%2Fdocs%2F%0Aproduction%3A%0A%20%20environment%3A%20production%0A%20%20production_environment%3A%20true%0A