build error _cffi_backend.so: Undefined PLT symbol "___tls_get_addr" (symnum = 156)

[daira]

While building Tahoe with cffi as a dependency:

​https://tahoe-lafs.org/buildbot-tahoe-lafs/builders/MM%20netbsd5%20i386%20warp/builds/51/steps/test-already-have-dep/logs/stdio

Traceback (most recent call last):
  File "setup.py", line 474, in <module>
    **setup_args
  File "/usr/pkg/lib/python2.6/distutils/core.py", line 152, in setup
    dist.run_commands()
  File "/usr/pkg/lib/python2.6/distutils/dist.py", line 975, in run_commands
    self.run_command(cmd)
  File "/usr/pkg/lib/python2.6/distutils/dist.py", line 995, in run_command
    cmd_obj.run()
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/develop.py", line 23, in run
    self.old_run()
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/develop.py", line 33, in old_run
    self.install_for_development()
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/develop.py", line 103, in install_for_development
    self.process_distribution(None, self.dist, not self.no_deps)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/easy_install.py", line 526, in process_distribution
    [requirement], self.local_index, self.easy_install
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/pkg_resources.py", line 580, in resolve
    dist = best[req.key] = env.best_match(req, self, installer)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/pkg_resources.py", line 838, in best_match
    return self.obtain(req, installer) # try and download/install
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/pkg_resources.py", line 850, in obtain
    return installer(requirement)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/easy_install.py", line 453, in easy_install
    return self.install_item(spec, dist.location, tmpdir, deps)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/easy_install.py", line 483, in install_item
    dists = self.install_eggs(spec, download, tmpdir)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/easy_install.py", line 663, in install_eggs
    return self.build_and_install(setup_script, setup_base)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/easy_install.py", line 938, in build_and_install
    self.run_setup(setup_script, setup_base, args)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/easy_install.py", line 927, in run_setup
    run_setup(setup_script, args)
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/sandbox.py", line 62, in run_setup
    lambda: execfile(
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/sandbox.py", line 105, in run
    return func()
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/sandbox.py", line 64, in <lambda>
    {'__file__':setup_script, '__name__':'__main__'}
  File "setup.py", line 338, in <module>
    
  File "/usr/pkg/lib/python2.6/distutils/core.py", line 152, in setup
    dist.run_commands()
  File "/usr/pkg/lib/python2.6/distutils/dist.py", line 975, in run_commands
    self.run_command(cmd)
  File "/usr/pkg/lib/python2.6/distutils/dist.py", line 994, in run_command
    cmd_obj.ensure_finalized()
  File "/usr/pkg/lib/python2.6/distutils/cmd.py", line 117, in ensure_finalized
    self.finalize_options()
  File "/home/tahoe/buildslave/tahoe/MM_netbsd5_i386_warp/build/setuptools-0.6c16dev5.egg/setuptools/command/bdist_egg.py", line 98, in finalize_options
    bdist_base = self.get_finalized_command('bdist').bdist_base
  File "/usr/pkg/lib/python2.6/distutils/cmd.py", line 319, in get_finalized_command
    cmd_obj.ensure_finalized()
  File "/usr/pkg/lib/python2.6/distutils/cmd.py", line 117, in ensure_finalized
    self.finalize_options()
  File "/usr/pkg/lib/python2.6/distutils/command/bdist.py", line 103, in finalize_options
    self.plat_name = self.get_finalized_command('build').plat_name
  File "/usr/pkg/lib/python2.6/distutils/cmd.py", line 319, in get_finalized_command
    cmd_obj.ensure_finalized()
  File "/usr/pkg/lib/python2.6/distutils/cmd.py", line 117, in ensure_finalized
    self.finalize_options()
  File "setup.py", line 106, in finalize_options
    "Programming Language :: Python :: 2.7",
  File "setup.py", line 83, in get_ext_modules
    "Environment :: Console",
  File "/tmp/easy_install-1ec6Y_/cryptography-0.6/cryptography/hazmat/primitives/constant_time.py", line 32, in <module>
  File "/tmp/easy_install-1ec6Y_/cryptography-0.6/cffi-0.8.6-py2.6-netbsd-6.1.2-i386.egg/cffi/api.py", line 56, in __init__
ImportError: /tmp/easy_install-1ec6Y_/cryptography-0.6/cffi-0.8.6-py2.6-netbsd-6.1.2-i386.egg/_cffi_backend.so: Undefined PLT symbol "___tls_get_addr" (symnum = 156)
program finished with exit code 1