update-manager doesn't reflect updates installed on the console meanwhile

[Karl-Philipp Richter]

After `sudo apt-get update` on console which found new updates available, `update-manager` pops up with a notification that this is the case with a noticable delay. If one ran `sudo apt-get dist-upgrade` in the meantime and `apt-get dist-upgrade` finished it appears strage to get a notification about updates which have just been installed.

The dialog should re-check the state right before being displayed and not be displayed in case `apt-get` is running or installed the updates already. And it'd be nice if the dialog could check in the background whether updates are installed while it was displayed and update it's content saying that new updates have been installed meanwhile (it shouldn't simply disappear since that causes users to wonder what that dialog was).

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: update-manager 1:17.10.11
ProcVersionSignature: Ubuntu 4.13.0-19.22-generic 4.13.13
Uname: Linux 4.13.0-19-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.7-0ubuntu3.6
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Fri Dec 15 15:35:43 2017
GsettingsChanges:
 b'com.ubuntu.update-manager' b'window-height' b'744'
 b'com.ubuntu.update-manager' b'first-run' b'false'
 b'com.ubuntu.update-manager' b'window-width' b'1301'
 b'com.ubuntu.update-manager' b'launch-time' b'int64 1513348134'
InstallationDate: Installed on 2015-12-12 (734 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
UpgradeStatus: Upgraded to artful on 2017-10-19 (56 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.