Merge branch 'xz/send-email-batch-size' into next

"git send-email" learned to complain when the batch-size option is
not defined when the relogin-delay option is, since these two are
mutually required.

* xz/send-email-batch-size:
send-email: error out when relogin delay is missing

diff --cc git-send-email.perl
Simple merge