We're trying to move away from the legacy pbr 'build_sphinx' command.
However, without the relevant section in the 'setup.cfg' file, we have
no way to determine if the user wishes to use the '-W'
(warning-is-error) flag when building docs. The current behavior for
this is to default to False, meaning documentation for projects that
previously used the pbr functionality to enable warning-is-error is
liable to slowly break as time passes.
To resolve this, default to True for packages with no [build_sphinx]
section in setup.cfg. This ensures that projects migrating to the new
PTI (which, when fully implemented, involves removing the [build_sphinx]
section from setup.cfg) will be forced to fix any warnings prior to the
migration. However, packages that have not been converted will not be
broken. Only pacakges that have already fully switched over to the new
PTI but which did not have warning-is-error enabled are at risk of
unexpected breakage, but even for those the short-term pain should
ultimately be outweighed by the long-term gain.
Change-Id: I677afef96370ead5a45cba854ba483f18a8d1247
a258aa9a3b