UnicodeEncodeError: 'ascii' codec can't encode character u'\u201c' in position 342: ordinal not in range(128)

[wtanaka]

% yolk --version
yolk 0.9

Steps to reproduce:

% yolk -M idna==2.6 | cat
Traceback (most recent call last):
  File "........../venv/bin/yolk", line 11, in <module>
maintainer: 
docs_url: None
project_url: []
maintainer_email: 
cheesecake_code_kwalitee_id: None
obsoletes_dist: []
keywords: 
package_url: https://pypi.org/project/idna/
requires_external: []
author: Kim Davies
home_page: https://github.com/kjd/idna
download_url: 
platform: 
version: 2.7
obsoletes: []
provides: []
cheesecake_documentation_id: None
_pypi_hidden: False
    sys.exit(main())
  File ".......site-packages/yolk/cli.py", line 1171, in main
    my_yolk.run()
  File ".......site-packages/yolk/cli.py", line 224, in run
    return getattr(self, action)()
  File ".......site-packages/yolk/cli.py", line 692, in query_metadata_pypi
    print(u'{}: {}'.format(key, metadata[key]))
  File ".......site-packages/yolk/cli.py", line 92, in write
    self.stdout.write(inline)
UnicodeEncodeError: 'ascii' codec can't encode character u'\u201c' in position 342: ordinal not in range(128)