Git question. Is there a way of duplicating a git repository?

[Alan Mackenzie]

Hello, Emacs.

Now that we've cut the emacs-25 release branch, I'd like to have a
distinct repository for this.

I could simply download another copy from savannah, but this would
(presumably) be a distinct copy, rather than hard linking the repository
files.  This would cost me disk (and backup) space.

Or I could clone my master repository to make emacs-25.  But this would
make the new repo firmly subordinate to the master repo, rather than
directly with savannah.

So, is there any convenient way of duplicating a repo (using hard links,
and preserving config info)?

-- 
Alan Mackenzie (Nuremberg, Germany).