Comment 38 for bug 402188

The description of this bug states:
"gvim works fine otherwise, it's just annoying to get these warnings."

But this is not true when issueing a bzr commit command without the -m or -F option:
if gvim is chosen as the editor in ~/.bazaar/bazaar.conf,
then gvim will not show the horizontal line that separates the commit message from the list of files that are changed in the commit.

I'll try Jeremy's patch now and report back if that behaviour is fixed.