pages: display a warning instead or raising exception if write fails: request.write sometimes raise an AttributeError. This case happens most of time when browser tab is closed or reloaded before the page has been written. fix 214

User-agent: *
Allow: /blog/
Allow: /u/
Allow: /b/
Disallow: /libervia.html
Disallow: /mr
Disallow: /login

User-agent: Mediapartners-*
Disallow: /