In this commit ( http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=08974112ae68aefba658a8516c8faa3374edc924 ), I am wondering why we have two bindings "%c" and "%g" call the same command?

Why not have just one binding? That way, the user's get used to the same binding; we won't have a split where some prefer %c and some prefer %g. Then there are no bad feelings when/if one of the bindings might need to be sacrificed in future for some reason.

OTOH, I am excited to try out this new feature.

Thanks!