I can confirm this is working in Xenial. After change the sshd_config config and execute a systemctl restart it worked. The ssh.service file have only one ExecReload clause:
... [Service] EnvironmentFile=-/etc/default/ssh ExecStart=/usr/sbin/sshd -D $SSHD_OPTS ExecReload=/bin/kill -HUP $MAINPID ...
I can confirm this is working in Xenial. After change the sshd_config config and execute a systemctl restart it worked. The ssh.service file have only one ExecReload clause:
... =-/etc/ default/ ssh /usr/sbin/ sshd -D $SSHD_OPTS /bin/kill -HUP $MAINPID
[Service]
EnvironmentFile
ExecStart=
ExecReload=
...