Using hg-git, TortoiseHg and github over https gives 401

I’m using hg-git with TortoiseHg to try to push my existing repository to GitHub. I’m authenticating with HTTPS, rather than SSH. I added my username and password to TortoiseHg just like for BitBucket.

But TortoiseHg says that the remove server gives 401.

All the examples I could find for authenticating with hg-git use SSH rather than HTTPS.

How can I convince TortoiseHg to cough up my username and password to GitHub?

Git Baby is a git and github fan, let's start git clone.