patch 8.2.0904: assuming modifyOtherKeys for rhs of mapping

Problem:    Assuming modifyOtherKeys for rhs of mapping.
Solution:   Ignore seenModifyOtherKeys for mapped characters. (closes #6200)
diff --git a/src/version.c b/src/version.c
index 399886e..3d24837 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    904,
+/**/
     903,
 /**/
     902,