python: Catch setsockopt exceptions for TCP stream.

'sock.setsockopt' could throw exceptions. For example, if non-blocking
connection failed before the call:

  Traceback (most recent call last):
    File "../.././test-ovsdb.py", line 896, in <module>
      main(sys.argv)
    File "../.././test-ovsdb.py", line 891, in main
      func(*args)
    File "../.././test-ovsdb.py", line 604, in do_idl
      ovs.stream.Stream.open(r))
    File "/root/git_/ovs/python/ovs/stream.py", line 190, in open
      error, sock = cls._open(suffix, dscp)
    File "/root/git_/ovs/python/ovs/stream.py", line 744, in _open
      sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
    File "/usr/local/lib/python2.7/socket.py", line 228, in meth
      return getattr(self._sock,name)(*args)
  socket.error: [Errno 54] Connection reset by peer

This fixes tests on FreeBSD.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

python/ovs/stream.py

@@ -361,6 +361,10 @@ def _open(suffix, dscp):
         error, sock = ovs.socket_util.inet_open_active(socket.SOCK_STREAM,
                                                        suffix, 0, dscp)
         if not error:
-            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+            try:
+                sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+            except socket.error as e:
+                sock.close()
+                return ovs.socket_util.get_exception_errno(e), None
         return error, sock
 Stream.register_method("tcp", TCPStream)