ipython segfaults

Steps to reproduce:

# pip install ipython
---------- 8< ----------
          SNIP
---------- 8< ----------
$ ipython
Python 2.7.12 (default, Jun 29 2016, 08:37:29)
Type "copyright", "credits" or "license" for more information.

IPython 5.0.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

[1]    11230 segmentation fault  ipython
$

Workaround:

# cd /usr/lib/python2.7/site-packages/prompt_toolkit/terminal/
# mv vt100_output.py vt100_output.py.bak
# sed '/fcntl/s/, True//' vt100_output.py.bak > vt100_output.py

Root cause:

By inspecting fcntlmodule.c Line 124 and fcntlmodule.c Line 174, we can see that depending on that fourth argument, the implementation differs greatly. Therefore I am posting this bug here since it might be related to Alpine (it doesn’t happen on Ubuntu, according to a user in irc.freenode.com#python).

(from redmine: issue id 5981, created on 2016-07-29)