--- a/hgext3rd/evolve/cmdrewrite.py	Thu Nov 30 12:14:36 2017 -0500
+++ b/hgext3rd/evolve/cmdrewrite.py	Sun Nov 12 01:26:30 2017 +0530
@@ -49,6 +49,18 @@
 
 # option added by evolve
 
+def _checknotesize(opts):
+    """ make sure note is of valid format """
+
+    note = opts.get('note')
+    if not note:
+        return
+
+    if len(note) > 255:
+        raise error.Abort(_("cannot store a note of more than 255 bytes"))
+    if '\n' in note:
+        raise error.Abort(_("note cannot contain a newline"))
+
 def _resolveoptions(ui, opts):
     """modify commit options dict to handle related options