2.7 is closed to new features. This looks like it mignt be one. The 2.7 doc for tarfile.open says "Return a TarFile object for the pathname name." Does the meaning of 'pathname' in 2.7 generally include unicode as well as str objects? (It is not in the Glossary.) 

> The error does not occur under Python 3 (even with non-ascii characters), so it should be possible to create a tarfile with a unicode filename on Python 2.7.

Python 3 has many new features that are not in 2.7, so 'possible' is not exactly the point ;-).