* lib/uri/generic.rb (URI::Generic.find_proxy): return nil if
  http_proxy environment variable is empty string.
  [ruby-core:57140] [Bug #8898]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42930 b2dd03c8-39d4-4d8f-98ff-823fe69b080e