912c96d408
1. Sphinx 1.8 introduced [1] the '--keep-going' argument which, as its name
suggests, keeps the build running when it encounters non-fatal errors.
This is exceptionally useful in avoiding a continuous edit-build loop
when undertaking large doc reworks where multiple errors may be
introduced.
2. pbr hasn't need the hook configuration since forever [2]
[1] https://github.com/sphinx-doc/sphinx/commit/e3483e9b045
[2] c84876dc0f
Change-Id: I22e930f9876ca29750093a78e4bf3a7d4a479eb9