Always set *socket_error to something appropriate when returning -1 from connection_connect()

changes/bug6028

@@ -0,0 +1,4 @@
+ o Minor bugfixes:
+   - Make sure to set *socket_error in all error cases in
+     connection_connect(), so it can't produce a warning about errno being
+     zero from errno_to_orconn_end_reason().  Resolves ticket 6028.

src/or/connection.c

@@ -1331,6 +1331,7 @@ connection_connect(connection_t *conn, const char *address,
 
   if (get_n_open_sockets() >= get_options()->_ConnLimit-1) {
     warn_too_many_conns();
+    *socket_error = ENOBUFS;
     return -1;
   }
 
@@ -1423,8 +1424,11 @@ connection_connect(connection_t *conn, const char *address,
          escaped_safe_str_client(address),
          port, inprogress?"in progress":"established", s);
   conn->s = s;
-  if (connection_add_connecting(conn) < 0) /* no space, forget it */
+  if (connection_add_connecting(conn) < 0) {
+    /* no space, forget it */
+    *socket_error = ENOBUFS;
     return -1;
+  }
   return inprogress ? 0 : 1;
 }