send-email: initial_to and initial_reply_to are both optional
We may pick up additional recipients from the format-patch output
files we are sending, in which case it is perfectly valid to leave
the @initial_to empty when the prompt asks. We may want to start
a new discussion thread without replying to anything, and it is
valid to leave $initial_reply_to empty.
An earlier update to avoid y@example.com stuffed in address fields
did not take these two cases into account.
Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>