Just for the record, and in case somebody looks: Some months ago, I spent considerable effort to "hunt down" that native remote-hg, and discovered that it exists in a usable state, albeit quite hidden in the msysgit repository. I extracted a version of this, which can be found here:
But note that to work properly, this one also needs a patch in the "git" binary itself, so you cannot just use it with a stock version of git! Unfortunately, those patch currently don't look as if they might be merged into git, but perhaps this will change. Anyway, I summarized my findings here:
Since then, another "native" remote-hg was created, which does not require git to be patched (though with some patches to git it works better, these are currently being reviewed). You can find it here:
And it has been working well for me for some time, though I did not yet test it really extensively.
Lately I've also been using @felipec's tool rather than my own, it's seems faster and is certainly better maintained these days. I added a note to the README here to point folks over there instead.