$ wget -N https://api.gentoo.org/packages/herds.xml --2015-12-05 22:31:59-- https://api.gentoo.org/packages/herds.xml Resolving api.gentoo.org (api.gentoo.org)... 89.16.167.134, 2001:41c8:0:936::136, 2001:41c8:0:936::139 Connecting to api.gentoo.org (api.gentoo.org)|89.16.167.134|:443... connected. HTTP request sent, awaiting response... 200 OK Server ignored If-Modified-Since header for file 'herds.xml'. You might want to add --no-if-modified-since option. I really think we should respect If-Modified-Since on api.g.o, to provide a clean and bandwidth-efficient way of retrieving new data.