MEDIUM: stream-interface: don't remove WAIT_DATA when a handshake is in progress

This doesn't make sense and will only require that it's enabled again.
diff --git a/src/stream_interface.c b/src/stream_interface.c
index 2c0364f..4ce8902 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -765,7 +765,6 @@
 
 	if (si->conn.flags & CO_FL_HANDSHAKE) {
 		/* a handshake is in progress */
-		si->flags &= ~SI_FL_WAIT_DATA;
 		return;
 	}
 
@@ -877,7 +876,6 @@
 	/* handshake running on producer */
 	if (si->conn.flags & CO_FL_HANDSHAKE) {
 		/* a handshake is in progress */
-		si->flags &= ~SI_FL_WAIT_DATA;
 		return;
 	}