Fix missing return

My bad.

Author: wvu

modules/exploits/multi/http/phoenix_exec.rb

@@ -61,7 +61,7 @@ def check
     test = Rex::Text.rand_text_alpha(8)
     res = http_send_command("echo #{test};")
     if res && res.body.include?(test)
-      Exploit::CheckCode::Vulnerable
+      return Exploit::CheckCode::Vulnerable
     end
     Exploit::CheckCode::Safe
   end