Error [Errno 89] Function not implemented while source installing catkin_pkg

edit

This is actually cross-posted on stackoverflow to ask as a general python question. Here I ask in ROSy way.

On QNX realtime OS, I'm trying to install catkin_pkg from source, and seeing the following error upon running pip.

# pip install -U catkin_pkg 
Downloading/unpacking catkin-pkg
  Running setup.py egg_info for package catkin-pkg

Requirement already up-to-date: argparse in /usr/pkg/lib/python2.7/site-packages (from catkin-pkg)
Requirement already up-to-date: docutils in /usr/pkg/lib/python2.7/site-packages (from catkin-pkg)
Requirement already up-to-date: python-dateutil in /usr/pkg/lib/python2.7/site-packages (from catkin-pkg)
Requirement already up-to-date: six in /usr/pkg/lib/python2.7/site-packages (from python-dateutil->catkin-pkg)
Installing collected packages: catkin-pkg
  Running setup.py install for catkin-pkg
    Error [Errno 89] Function not implemented while executing command /usr/qnx650/host/qnx6/x86/usr/bin/python -c "import setuptools;__file__='/tmp/pip-build-n130s/catkin-pkg/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-XhRdBe-record/install-record.txt --single-version-externally-managed
Exception:
Traceback (most recent call last):
  File "/usr/pkg/lib/python2.7/site-packages/pip-1.3-py2.7.egg/pip/basecommand.py", line 139, in main
    status = self.run(options, args)
  File "/usr/pkg/lib/python2.7/site-packages/pip-1.3-py2.7.egg/pip/commands/install.py", line 271, in run
    requirement_set.install(install_options, global_options, root=options.root_path)
  File "/usr/pkg/lib/python2.7/site-packages/pip-1.3-py2.7.egg/pip/req.py", line 1185, in install
    requirement.install(install_options, global_options, *args, **kwargs)
  File "/usr/pkg/lib/python2.7/site-packages/pip-1.3-py2.7.egg/pip/req.py", line 592, in install
    cwd=self.source_dir, filter_stdout=self._filter_install, show_stdout=False)
  File "/usr/pkg/lib/python2.7/site-packages/pip-1.3-py2.7.egg/pip/util.py", line 627, in call_subprocess
    cwd=cwd, env=env)
  File "/usr/pkg/lib/python2.7/subprocess.py", line 711, in __init__
    errread, errwrite)
  File "/usr/pkg/lib/python2.7/subprocess.py", line 1205, in _execute_child
    self.pid = os.fork()
OSError: [Errno 89] Function not implemented
Storing complete log in /root/.pip/pip.log

The first time I ran this pip command when the depended components (such as argparse, docutils, python-dateutil and six) were not installed, the same error happened too, but not during installation of catkin_pkg but while checking these required components are installed. Now that I've installed them one by one, it seems to be happening at while installing catkin_pkg itself.

On python's console, os.fork(), which I assumed is the root cause, behaves differently. Thus I'm not even sure if the error occurs at os.fork() or somewhere different.

# python
Python 2.7.4 (default, Jun 21 2013, 22:33:48) 
[GCC 4.4.2] on qnx6
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.fork()
18804790
>>> 0
sem_wait: Invalid argument

How can I avoid this error? Thank you!

Using QNX 6.5.0 SDP SP1, pip version is 1.3 (its source on github)

Update) When trying to install bloom via pip the same error happened.