update-manager creates duplicate snapper "pre" snapshots

[R1dO]

This system uses a btrfs filesystem in combination with snapper.

Via the file ``/etc/apt/apt.conf.d/80snapper`` (default file from repositories) it is configured to take pre-post snapshots upon performing any apt driven changes.

When using the update-manager i noticed 2 pre-snapshots are created at approximately the same time when upgrading. Leading to a snapper warning ``THROW: illegal snapshot`` for post upgrade actions.

In order to rule out ``snapper`` or ``apt`` as a source i tested the other methods (known to me) for upgrading packages, none of them showing the error (see table below):

================ | ==================
Case | # of pre snapshots
================ | ==================
Synaptic updates | 1
Update Manager | 2 <-
apt upgrade | 1
apt-get upgrade | 1
================ | ==================

I suspect the upgrade-manager makes 2 DPkg::Pre-Invoke calls when this happens. But i'm too unfamiliar with this package to do any real bug hunting.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: update-manager 1:17.04.8
ProcVersionSignature: Ubuntu 4.10.0-38.42-generic 4.10.17
Uname: Linux 4.10.0-38-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.5
Architecture: amd64
CurrentDesktop: XFCE
Date: Mon Nov 13 22:41:48 2017
GsettingsChanges:
 b'com.ubuntu.update-manager' b'show-details' b'true'
 b'com.ubuntu.update-manager' b'window-height' b'1390'
 b'com.ubuntu.update-manager' b'first-run' b'false'
 b'com.ubuntu.update-manager' b'window-width' b'2560'
 b'com.ubuntu.update-manager' b'launch-time' b'int64 1510607283'
InstallationDate: Installed on 2016-12-21 (327 days ago)
InstallationMedia: Xubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: Upgraded to zesty on 2017-04-16 (211 days ago)

p.s. edited the table to have a visual separation of the columns

[dino99 (9d9)]

That version is now dead
http://news.softpedia.com/news/ubuntu-17-04-zesty-zapus-has-reached-end-of-life-upgrade-to-ubuntu-17-10-now-519360.shtml

[R1dO (r-den-ouden)]

I believe it is a bit premature to mark this as invalid, due to an external (non ubuntu) website telling 17.04 has reached end-of life.

Even though the bug report might have surfaced in 17.04, there has not been any information mentioning it is fixed in more recent ubuntu (or update-manager) versions.

[dino99 (9d9)]

you are right, but:
- ubuntu has set 17.04 EOL itself
- btrfs is still in his early days; so not really linked to the package report
- and no one else but you has pointed that issue

So lets moving on with more recent versions; that report is useless .

[Brian Murray (brian-murray)]

This should not just be closed because Zesty has become end of life, this sounds like a real bug and the update-manager code around snapshots has not changed at all recently.