[web/httpcache] send weak ETags There's no way we can provide a strong validator in general (especially considering how ETags are generated by the current EtagHTTPCacheManager and EntityHTTPCacheManager). So mark our entity-tags as weak.

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
https://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))