patch 7.4.2223
Problem:    Buffer overflow when using latin1 character with feedkeys().
Solution:   Check for an illegal character.  Add a test.
diff --git a/src/testdir/test_alot_utf8.vim b/src/testdir/test_alot_utf8.vim
index 049251f..539e0e1 100644
--- a/src/testdir/test_alot_utf8.vim
+++ b/src/testdir/test_alot_utf8.vim
@@ -8,3 +8,4 @@
 source test_expr_utf8.vim
 source test_matchadd_conceal_utf8.vim
 source test_regexp_utf8.vim
+source test_source_utf8.vim