git send-email could check for no To: line

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

I keep coming up with new and innovative ways to send stupid-looking
emails with git send-email.  Please save me from myself.

My latest SNAFU is to spend so much time setting up the 'cc' list in
the git-format-patch step that I completely forgot to put anybody on the
'to' line, and even being prompted by git send-email that I might want
to add somebody to the 'To' line wasn't enough.

Could there be an extra confirmation, perhaps in send_message() that

        if ($cc ne '' && $to eq '')
		are_you_sure()

(you don't want me writing perl.  you really don't.)