patch 7.4.1902

Problem:    No test for collapsing buffers for a channel.  Some text is lost.
Solution:   Add a simple test.  Set rq_buflen correctly.

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1902,
 /**/
     1901,
 /**/