config: reject str sections and keys on Python 3
Otherwise we could end up with a dict having both the str
and bytes versions of a particular config item. This may cause
some tests to regress. I haven't checked. But it is better
behavior to fail fast.
We could just as easily change this to normalize the values. But
I like catching all non-compliant call sites first.
Differential Revision: https://phab.mercurial-scm.org/D5649
max_width = 79
wrap_comments = true
error_on_line_overflow = true