The breakage was fixed with pyVows 2.0.6. I've reported this
dependency change upstream with [1].
[1]: https://github.com/rafaelcaricio/tornado_pyvows/pull/15
RDEPEND="
dev-python/pycurl[${PYTHON_USEDEP}]
- <=dev-python/pyvows-2.0.3[${PYTHON_USEDEP}]
+ dev-python/pyvows[${PYTHON_USEDEP}]
+ !=dev-python/pyvows-2.0.4[${PYTHON_USEDEP}]
+ !=dev-python/pyvows-2.0.5[${PYTHON_USEDEP}]
dev-python/urllib3[${PYTHON_USEDEP}]
www-servers/tornado[${PYTHON_USEDEP}]
"