Remove deleted pages when updating online HTML

[Mariatta]

Based on discussions in: python/devguide#114

Seems like docsbuild script doesn't remove html for docs that have been deleted.

Thanks @ned-deily and @zware for pointing me this way.

[JulienPalard]

I took a rapid look, current script uses a cp -a, using an rsync -a --delete-delay would correctly old files.

[JulienPalard]

Merged this a few hours ago, it should no longer happen.

logs from docs.iad1.psf.io:

[…]
DEBUG:2017-08-30 15:07:58,378:Running command 'rsync -a --delete-delay /srv/docsbuild/devguide/build/html/ /srv/docs.python.org/devguide'
[…]

[Mariatta]

Yay! Thanks @JulienPalard 🌮