python: Catch exception "SSL.SysCallError" for send by SSL.

When OVSDB server is aborted,
the SSL send function will throw SSL.SysCallError exception,
which we need to catch and return it's -errno.

While SSL.WantWriteError exception needs to return -EAGAIN
based on its parent class, not EAGAIN

Signed-off-by: Guoshuai Li <ligs@dtdream.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

python/ovs/stream.py

@@ -809,7 +809,9 @@ class SSLStream(Stream):
                 buf = buf.encode('utf-8')
             return super(SSLStream, self).send(buf)
         except SSL.WantWriteError:
-            return errno.EAGAIN
+            return -errno.EAGAIN
+        except SSL.SysCallError as e:
+            return -ovs.socket_util.get_exception_errno(e)
 
 
 if SSL: