pip crashes when reinstalling native wheels

[Dan Kegel]

On Ubuntu 18.04 (and ,
Running 'pip install simplejson' or 'pip install PyOpenSSL' twice
crashes on exit because their shared libraries are overwritten while in use.

To reproduce:

$ sudo apt install python-pip
$ pip install simplejson
$ pip install simplejson
Segmentation fault (core dumped)

Running (on some machines, at least) under gdb is illuminating:
$ sudo apt install python-dbg
$ gdb python
(gdb) set args -m pip install simplejson
(gdb) run
Starting program: /usr/bin/python -m pip install simplejson
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Collecting simplejson
Installing collected packages: simplejson
Successfully installed simplejson-3.16.0

Program received signal SIGSEGV, Segmentation fault.
0x000055555562ae84 in visit_decref () at ../Modules/gcmodule.c:360
360 ../Modules/gcmodule.c: Datei oder Verzeichnis nicht gefunden.
(gdb) bt
#0 0x000055555562ae84 in visit_decref ()
    at ../Modules/gcmodule.c:360
#1 0x000055555562b004 in dict_traverse.lto_priv ()
    at ../Objects/dictobject.c:2198
#2 0x0000555555629da5 in subtract_refs ()
    at ../Modules/gcmodule.c:385
#3 collect.lto_priv () at ../Modules/gcmodule.c:925
#4 0x0000555555686721 in PyGC_Collect ()
    at ../Modules/gcmodule.c:1440
#5 0x0000555555685923 in Py_Finalize () at ../Python/pythonrun.c:455
#6 0x00005555556a9bc8 in Py_Exit (sts=sts@entry=0)
    at ../Python/pythonrun.c:1792

That backtrace that looks similar to
https://github.com/pypa/pip/issues/5366

Happily, the fix that was committed for the bug seems simple and plausible, and cherrypicking it seems to prevent the crash.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: python-pip 9.0.1-2.3~ubuntu1
ProcVersionSignature: User Name 4.15.0-46.49-generic 4.15.18
Uname: Linux 4.15.0-46-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
Date: Sat Mar 23 21:46:31 2019
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
SourcePackage: python-pip
UpgradeStatus: No upgrade log present (probably fresh install)

[Dan Kegel (dank)]

https://launchpad.net/~dank/+archive/ubuntu/python-fixes contains an updated pip with the cherrypicked fix.
(Also, http://kegel.com/linux/howto-ppa/ happens to document how it was prepared.)

[Dan Kegel (dank)]

The first line of the bug report should have said "and ubuntu 16.04".

https://launchpad.net/~dank/+archive/ubuntu/python-fixes/+packages now includes
updated pip with the cherrypicked fix for both ubuntu 16.04 and ubuntu 18.04.

[Launchpad Janitor (janitor)]

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

[Kai Kasurinen (kai-kasurinen)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. However, I am closing it because the bug has been fixed in the current version of Ubuntu.