Hello,

I am getting the following error while installing eggs

UnknownExtra: html5lib 0.9999999 has no such extra feature 'datrie'

I am using two libraries nti.contentfragments which has in its setpy.py/install_requires
[
'setuptools',
'html5lib[datrie]', # > 1.0.1
...

and google tensorflow which has a hard requirement for
html5lib = 0.9999999

I am pinning html5lib to 0.9999999 in my version.cfg; however; instead of getting a warning
(i.e. html5lib 10.9999999 does not provide the extra 'datrie') like when installing a package in pip, I get the exception mentioned above.

Thanks

Carlos