I got the problem when installing a package with resources using pysetup3. Here's the relevant part of the console session:

(venv) vinay@eta-natty:~/projects$ pysetup3 install nemo
Installing from source directory: /home/vinay/projects/nemo
running install_dist
running build
running build_py
running build_scripts
running install_lib
creating /tmp/venv/lib/python3.3/site-packages
creating /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper
byte-compiling /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper/hook_loader.py to hook_loader.pyc
byte-compiling /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper/user_scripts.py to user_scripts.pyc
byte-compiling /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper/__init__.py to __init__.pyc
byte-compiling /tmp/venv/lib/python3.3/site-packages/nemo.py to nemo.pyc
running install_scripts
changing mode of /tmp/venv/bin/nemo to 755
running pre_hook hooks.pre_install_data for command install_data
running install_data
running install_distinfo
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/METADATA
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/INSTALLER
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/REQUESTED
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/RESOURCES
Traceback (most recent call last):
  File "/tmp/venv/bin/pysetup3", line 6, in <module>
    rc = packaging.run.main() # None interpreted as 0
  File "/usr/local/lib/python3.3/packaging/run.py", line 653, in main
    return dispatcher()
  File "/usr/local/lib/python3.3/packaging/run.py", line 642, in __call__
    return func(self, self.args)
  File "/usr/local/lib/python3.3/packaging/run.py", line 91, in wrapper
    return f(*args, **kwargs)
  File "/usr/local/lib/python3.3/packaging/run.py", line 164, in _install
    return not install_local_project(target)
  File "/usr/local/lib/python3.3/packaging/install.py", line 122, in install_local_project
    return _run_install_from_dir(path)
  File "/usr/local/lib/python3.3/packaging/install.py", line 160, in _run_install_from_dir
    func(source_dir)
  File "/usr/local/lib/python3.3/packaging/install.py", line 87, in _run_packaging_install
    dist.run_command('install_dist')
  File "/usr/local/lib/python3.3/packaging/dist.py", line 709, in run_command
    cmd_obj.run()
  File "/usr/local/lib/python3.3/packaging/command/install_dist.py", line 508, in run
    self.run_command(cmd_name)
  File "/usr/local/lib/python3.3/packaging/command/cmd.py", line 330, in run_command
    self.distribution.run_command(command)
  File "/usr/local/lib/python3.3/packaging/dist.py", line 709, in run_command
    cmd_obj.run()
  File "/usr/local/lib/python3.3/packaging/command/install_distinfo.py", line 113, in run
    writer.writerow(row)
TypeError: 'str' does not support the buffer interface

This is the relevant code in install_distinfo.run():

                resources_path = os.path.join(self.distinfo_dir,
                                              'RESOURCES')
                logger.info('creating %s', resources_path)
                if not self.dry_run:
                    #with open(resources_path, 'w', encoding='utf-8') as f:
                    with open(resources_path, 'wb') as f:
                        writer = csv.writer(f, delimiter=',',
                                            lineterminator='\n',
                                            quotechar='"')
                        for row in install_data.get_resources_out():
                            writer.writerow(row)

If I substitute the commented out line above which replaces 'wb' with 'w' and encoding, I get this result:

(venv) vinay@eta-natty:~/projects$ pysetup3 install nemo
Installing from source directory: /home/vinay/projects/nemo
running install_dist
running build
running build_py
running build_scripts
running install_lib
byte-compiling /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper/hook_loader.py to hook_loader.pyc
byte-compiling /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper/user_scripts.py to user_scripts.pyc
byte-compiling /tmp/venv/lib/python3.3/site-packages/virtualenvwrapper/__init__.py to __init__.pyc
byte-compiling /tmp/venv/lib/python3.3/site-packages/nemo.py to nemo.pyc
running install_scripts
changing mode of /tmp/venv/bin/nemo to 755
running pre_hook hooks.pre_install_data for command install_data
running install_data
running install_distinfo
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/METADATA
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/INSTALLER
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/REQUESTED
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/RESOURCES
creating /tmp/venv/lib/python3.3/site-packages/nemo-0.1.dist-info/RECORD