InstallationError: don't search issues on < 1.8.6

open-uri on Ruby pre-1.8.6 simply will not open https URLs at all,
making it impossible to check the Github API using the same method
as Homebrew.

This may only be disabled temporarily until the issue search is
rewritten, for example to use the curl helper.

Library/Homebrew/exceptions.rb

@@ -153,7 +153,7 @@ class BuildError < Homebrew::InstallationError
       end
     end
     puts
-    unless issues.empty?
+    unless RUBY_VERSION < "1.8.6" || issues.empty?
       puts "These open issues may also help:"
       puts issues.map{ |s| "    #{s}" }.join("\n")
     end