purging ureadahead leaves a systemd timer around

I removed ureadahead with apt-get purge ureadahead and found that it left a timer installed:

$ systemctl list-timers
NEXT LEFT LAST PASSED UNIT
Wed 2016-05-11 01:20:29 PDT 5h 50min left Tue 2016-05-10 01:20:28 PDT 18h ago systemd-tmpfiles-clean.t
Wed 2016-05-11 06:55:11 PDT 11h left Tue 2016-05-10 18:41:18 PDT 48min ago apt-daily.timer
n/a n/a Sat 2016-04-30 00:59:53 PDT 1 weeks 3 days ago ureadahead-stop.timer

Thanks

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ureadahead (not installed)
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Tue May 10 19:30:21 2016
InstallationDate: Installed on 2012-10-18 (1300 days ago)
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
SourcePackage: ureadahead
UpgradeStatus: Upgraded to xenial on 2016-04-30 (10 days ago)