Comment 14 for bug 1562733

Julian - I just tried and it seems like Post-Invoke is run when there is a W: but not an E: - is that right?

In this snippet I've added an Apt::Update::Post-Invoke { "echo 'hello' }

Reading package lists... Done
W: http://dl.google.com/linux/musicmanager/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1)
W: http://dl.google.com/linux/talkplugin/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1)
W: http://ppa.launchpad.net/pitti/systemd/ubuntu/dists/trusty/Release.gpg: Signature by key FB322597BBC86D52FEE950E299B656EA8683D8A2 uses weak digest algorithm (SHA1)
E: Failed to fetch http://dl.google.com/linux/musicmanager/deb/dists/stable/Release No Hash entry in Release file /var/lib/apt/lists/dl.google.com_linux_musicmanager_deb_dists_stable_Release which is considered strong enough for security purposes
E: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/Release No Hash entry in Release file /var/lib/apt/lists/dl.google.com_linux_talkplugin_deb_dists_stable_Release which is considered strong enough for security purposes
E: Some index files failed to download. They have been ignored, or old ones used instead.
laney@raleigh>

...and then after removing the google repositories:

Hit:10 http://ppa.launchpad.net/pitti/systemd/ubuntu trusty Release
hello
Reading package lists... Done
Building dependency tree
Reading state information... Done
9 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: http://ppa.launchpad.net/pitti/systemd/ubuntu/dists/trusty/Release.gpg: Signature by key FB322597BBC86D52FEE950E299B656EA8683D8A2 uses weak digest algorithm (SHA1)
laney@raleigh>
I see <https://anonscm.debian.org/cgit/apt/apt.git/tree/apt-pkg/update.cc#n108> which looks like it's where the function is returning from (didn't trace it though), which would prevent the Post-Inboke hook from running.