Bit rot breaking shared library references in packages not rebuilt in new Ubuntu releases

[Mechanical snail]

There is an issue where old package versions are getting released for newer Ubuntu releases without properly updating the shared-library references. This causes regressions where a package that worked in previous versions starts to fail with an error like:

photoprint: error while loading shared libraries: libgutenprint.so.2: cannot open shared object file: No such file or directory

The underlying issue seems to cause reappearing bugs like bug #260849, where the photoprint package refers to libgutenprint.so.2 (the file in current Ubuntu releases is libgutenprint.so.3).

This was discussed in Ask Ubuntu chat: http://chat.stackexchange.com/rooms/201/conversation/bug-1120870, http://chat.stackexchange.com/rooms/201/conversation/more-bug-discussion

What we guess is happening is that when a new Ubuntu release appears, binary packages with no source changes are copied unmodified into the newer Ubuntu repository. It apparently does not check that the package still works, or specifically that needed shared libraries still exist. What should happen is that the package gets rebuilt when needed (simply rebuilding the package gets it to work again: http://chat.stackexchange.com/transcript/message/8047931#8047931).

[Launchpad Janitor (janitor)]

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

[Andrew King (aking1012-com)]

Adding a comment for completeness:

I was initially dismissive of a bug against photoprint here: https://bugs.launchpad.net/ubuntu/+source/photoprint/+bug/260849/

Then I tried it with both binary packages and source packages. The binary package failed. The source package succeeded. This clearly indicates a problem with auto-builds or version control. I recommended a work-around until such time that the root problem is fixed, but it is an issue.

Thanks and have a great day.

:)

I thought what I'd do was, I'd pretend I was one of those deaf-mutes.

[William Grant (wgrant)]

It's not an issue with any Ubuntu-wide infrastructure: just with the involved packages and their dependencies.

In the case you referenced (bug #260849), Intrepid's photoprint binary package depends on libgutenprint2, presumably because it needs libgutenprint.so.2, but Intrepid's libgutenprint2 package only includes libgutenprint.so.1. The package's dependencies are incorrectly declared, or the dependency broke its interface. This isn't something that automated Launchpad or Ubuntu tools are meant to be able to detect; it's just a straight package bug

Your assumption about what happens when a new Ubuntu release appears is somewhat correct. All binaries and sources from the previous release are copied into the new one, all at once. This means it starts off just as consistent as the previous release was, as it contains exactly the same set of package versions. Things can only break when people upload new packages later on, and those packages have buggy dependency lists.