Commits on Nov 17, 2016

1. download: If we have a last-modified date, set the mtime of the targe… …

   …t file
   
   This only works for HTTP, not FTP.
   
   Should hopefully fix asgen considering suites as changed each time,
   which I think happened because the Packages file got the current mtime,
   so it was always considered to be newer.
   
   Fixes ximion#35

   Iain Lane committed Nov 17, 2016
   60389d7