This code is a backport from the upstream OVS (commit dcb66da):
If the loop condition in Stream.connect() was false, which is especially
likely for TCP connections, then Stream.connect() would return None,
which violates its documented behavior. This commit fixes the problem.
Reported-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>