Check that initial response doesn't contain invalid characters. Give better error message in case that happens.
Check that initial response doesn't contain invalid characters. Give better
error message in case that happens.

--HG--
branch : HEAD

jkerihuel/dovecot,dscho/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,dscho/dovecot,jkerihuel/dovecot,dscho/dovecot,dscho/dovecot,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jwm/dovecot-notmuch,dscho/dovecot,jkerihuel/dovecot