I searched Debian's packages and it looks like they've removed Nginx from the stable distribution (Jessie). It looks to be temporary as it's still in Sid, but I can't find any information on Debian's site. Does this indicate a problem with the previously available packages? From what's on my machine, the previously available version was 1.6.2.Here are the search results, although they're liable to change when Nginx gets reintroduced:
https://packages.debian.org/search?keywords=nginx&searchon=names&exact=1&suite=all§ion=all