Merge pull request #922 from horus42/master

Fixed potential SEGFAULT in socket_base.cpp

src/socket_base.cpp

@@ -121,10 +121,13 @@ zmq::socket_base_t *zmq::socket_base_t::create (int type_, class ctx_t *parent_,
             errno = EINVAL;
             return NULL;
     }
-
     alloc_assert (s);
-    if (s->mailbox.get_fd () == retired_fd)
+
+    if (s->mailbox.get_fd () == -1)
+    {
+        delete s;
         return NULL;
+    }
 
     return s;
 }