BUG/MINOR: cli: Don't close when SE_FL_ERR_PENDING is set in cli analyzer

BUG/MINOR: cli: Don't close when SE_FL_ERR_PENDING is set in cli analyzer

SE_FL_ERR_PENDING is used to report an error on the write side. But it is
not a terminal error. Some incoming data may still be available. In the cli
analyzers, it is important to not close the stream when this flag is
set. Otherwise the response to a command can be truncated. It is probably
hard to observe. But it remains a bug.

While this patch could be backported to 2.7, there is no real reason to do
so, except if someone reports a bug about truncated responses.