Crypt the text in the undo file if the file itself is crypted.
diff --git a/runtime/doc/undo.txt b/runtime/doc/undo.txt
index 96ff96a..e8fed4f 100644
--- a/runtime/doc/undo.txt
+++ b/runtime/doc/undo.txt
@@ -225,6 +225,9 @@
Undo files are normally saved in the same directory as the file. This can be
changed with the 'undodir' option.
+When the file is encrypted, the text in the undo file is also crypted. The
+same key and method is used. |encryption|
+
You can also save and restore undo histories by using ":wundo" and ":rundo"
respectively:
*:wundo* *:rundo*