net/http/header.rb: remove a hack

* lib/net/http/header.rb (Net::HTTPHeader#set_range): remove a hack
  for the bug fixed at [Bug #8739].

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42403 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/net/http/header.rb

@@ -238,7 +238,6 @@ module Net::HTTPHeader
     when Range
       first = r.first
       last = r.last
-      last -= 1 if r.exclude_end?
       if last == -1
         rangestr = (first > 0 ? "#{first}-" : "-#{-first}")
       else