using gvim as editor on Windows

I'd prefer to use gvim as an editor on Windows XP instead of vim. (I also
prefer it as a difftool, but that's a separate issue.) Gvim releases
the terminal when it launches, which git doesn't like too much. So I
create gvimf.cmd in my path and use it for core.editor. Gvimf.cmd is
quite simple; it calls:
	start "dummy" /b /wait "C:\Program Files\Vim\vim72\gvim.exe" %*

In .gitconfig:
[core]
	editor = gvimf.cmd

This works well enough for git commit. However, git rebase -i is not
happy. It errors:
	C:\path to\repo> git rebase -i HEAD~10
	The system cannot find the file dummy.
	Could not execute editor

Okay, I can fix that. I change core.editor to "cmd \\/c gvimf.cmd". (This
is the same pattern I use for gvim as a difftool.) Now my .gitconfig has:
[core]
	editor = cmd \\\\/c gvimf.cmd

Git rebase is happy, but git commit is not. It errors:
	C:\path to\repo> git commit
	'OMMIT_EDITMSG' is not recognized as an internal or external command,
	operable program or batch file.
	error: There was a problem with the editor 'cmd \\/c gvimf.cmd'.
	Please supply the message using either -m or -F option.

In the selfish hope to avoid work, has anyone else already encountered and solved how to use gvim as an editor?

Tait