Merge pull request rapid7#91 from jduck/master

Stack trace fix when mytarget is nil, actually populate the agent variable.

Author: Tod Beardsley

modules/exploits/windows/browser/ms11_050_mshtml_cobjectelement.rb

@@ -152,6 +152,7 @@ def on_request_uri(cli, request)
 		if target.name == 'Automatic'
 			mytarget = auto_target(cli, request)
 			if mytarget.nil?
+				agent = request.headers['User-Agent']
 				print_error("Unknown User-Agent #{agent} from #{cli.peerhost}:#{cli.peerport}")
 				send_not_found(cli)
 				return