hg-git with git pull request

[Neal Becker]

I'm maintaining a local copy of a github repo, to which I've locally added a 
PR.  So I create this by:

git clone https://github.com/QuantStack/xtensor.git
git fetch origin pull/269/head:dynamic_view

Now I can hg clone this local repo.

But can I create the hg copy directly from github, without the extra step of 
cloning the git local copy and then adding the PR?

I hope I'm making sense, I don't know much about git or github.