python3-libtorrent linking libboost_python27.so instead of libboost_python36.so

[stupid user]

[Impact]

Due to the libboost-python naming convention changing, python3-libtorrent incorrectly links to libboost_python27.so instead of libboost_python36.so in cosmic. The essentially renders the package useless.

[Test Case]

Run the command:

$ python3 -c "import libtorrent"

With 1.1.9-1 on cosmic, it will fail with:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: /usr/lib/x86_64-linux-gnu/libboost_python27.so.1.67.0: undefined symbol: PyClass_Type

The command should exit without error in the fixed version.

[Regression Potential]

There is little regression potential as the package is currently broken without this fix.

----

An error occurs when importing the libtorrent module from python 3.x script:

ImportError: /usr/lib/x86_64-linux-gnu/libboost_python27.so.1.67.0: undefined symbol: PyClass_Type

How to reproduce:
1. Install packages:
python36
python3-libtorrent
2. Run any python script importing libtorrent module

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: python3-libtorrent 1.1.9-1
ProcVersionSignature: Ubuntu 4.18.0-10.11-generic 4.18.12
Uname: Linux 4.18.0-10-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.10-0ubuntu13
Architecture: amd64
CurrentDesktop: XFCE
Date: Sat Oct 27 09:21:43 2018
InstallationDate: Installed on 2009-11-28 (3254 days ago)
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
SourcePackage: libtorrent-rasterbar
UpgradeStatus: Upgraded to cosmic on 2018-10-25 (1 days ago)

[Cas (calumlind)]

The issue seems to be that in Cosmic the libboost-python lib naming convention has changed and that affects the debian rules scripts picking the correct lib python version.

Bionic: /usr/lib/x86_64-linux-gnu/libboost_python-py36.so.1.62.0
Cosmic: /usr/lib/x86_64-linux-gnu/libboost_python36.so.1.67.0

https://packages.ubuntu.com/bionic/amd64/libboost-python1.62.0/filelist
https://packages.ubuntu.com/cosmic/amd64/libboost-python1.67.0/filelist

[Cas (calumlind)]

So the backward compatibility links were broken in libboost_python 1.67:

https://salsa.debian.org/debian/boost/commit/264a065b6996f87b3825afdc679474faff78d748#8756c63497c8dc39f7773438edf53b220c773f67_185_182

There is the new:

libboost_python$(py3default).so

The old:

libboost_python3-py$(py3default).so

But the other old name is missing:

libboost_python-py$(py3default).so

[Cas (calumlind)]

Upstream merge request created: https://salsa.debian.org/debian/boost/merge_requests/4

[Launchpad Janitor (janitor)]

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

[Cas (calumlind)]

Created a debdiff to fix the 1.1.9 package on Cosmic.

For reference to easily replicate the bug:

    apt install python3-libtorrent
    python3 -c 'import libtorrent as lt; print(lt.__version__)'

[Cas (calumlind)]

This won't be fixed in upstream boost package so instead I have made an upstream request to fix the package that should propagate to Disco https://salsa.debian.org/debian/libtorrent-rasterbar/merge_requests/1

In the meantime for any users needing a fixed version, there is a daily build PPA: https://code.launchpad.net/~libtorrent.org/+archive/ubuntu/rc-1.1-daily

[Launchpad Janitor (janitor)]

This bug was fixed in the package libtorrent-rasterbar - 1.1.11-2

---------------
libtorrent-rasterbar (1.1.11-2) unstable; urgency=medium

  * d/rules: Use boost-python >=1.67 soname suffix to fix
    Python 3 linking (LP: #1800264).

 -- Calum Lind <email address hidden> Sat, 08 Dec 2018 21:49:08 -0500

[Brian Murray (brian-murray)]

It doesn't seem worth fixing but the debdiff has an extraneous line removal in debian/changelog.

[Brian Murray (brian-murray)]

Hello stupid, or anyone else affected,

Accepted libtorrent-rasterbar into cosmic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/libtorrent-rasterbar/1.1.9-1ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-cosmic to verification-done-cosmic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-cosmic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Cas (calumlind)]

Thanks Brian, weirdly missed receiving notification about this update so would have checked sooner!

I have tested the 1.1.9-1ubuntu0.1 package and confirm it works.

[Launchpad Janitor (janitor)]

This bug was fixed in the package libtorrent-rasterbar - 1.1.9-1ubuntu0.1

---------------
libtorrent-rasterbar (1.1.9-1ubuntu0.1) cosmic; urgency=medium

  * Fix linking to wrong boost_python with Python 3. (LP: #1800264)

 -- Calum Lind <email address hidden> Wed, 05 Dec 2018 11:12:55 +0000

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for libtorrent-rasterbar has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Brian Murray (brian-murray)]

Ubuntu 18.10 (Cosmic Cuttlefish) has reached end of life, so this bug will not be fixed for that specific release.