MINOR: stream-int: Notify caller when an error is reported after a rcv_pipe()

In si_cs_send(), when an error is found on the CS or the connection at the
beginning of the function, we return 1 to notify the caller some processing may
be triggered. So, it seems logical to do the same after the call to rcv_pipe().

This patch is not flagged as a bug because no strange behaviour was yet observed
without it. It is just a proactive fix to be consistent.
diff --git a/src/stream_interface.c b/src/stream_interface.c
index 1f82959..cf3f9d2 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -625,7 +625,7 @@
 		}
 
 		if (conn->flags & CO_FL_ERROR || cs->flags & CS_FL_ERROR)
-			return 0;
+			return 1;
 	}
 
 	/* At this point, the pipe is empty, but we may still have data pending