patch 7.4.1826

Problem:    Callbacks are invoked when it's not safe. (Andrew Stewart)
Solution:   When a channel is to be closed don't invoke callbacks right away,
            wait for a safe moment.

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1826,
 /**/
     1825,
 /**/