patch 7.4.1257

Problem:    Channel test fails in some configurations.
Solution:   Add check for the +channel feature.

src/version.c

@@ -742,6 +742,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1257,
 /**/
     1256,
 /**/