timesyncd is not stopped when ntp is first installed

[Gavin Panella]

In Xenial, /lib/systemd/system/systemd-timesyncd.service.d/disable-with-time-daemon.conf ensures that systemd-timesyncd.service does not _start_ when ntp is installed, but when installing ntp for the first time nothing stops systemd-timesyncd before ntp is started: they're both running at the same time.

It could be some time between installing ntp and, say, rebooting, during which time both services will be trying to manage the local clock. This might not matter much for a client, but might be important for an NTP server.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Mon Jul 18 12:17:25 2016
SourcePackage: ntp
UpgradeStatus: No upgrade log present (probably fresh install)