When manually executing an upgrade, a prefix "Manual Upgrade: " is added to the current comment so that we know the update was run manually.

While convenient, this is cumbersome and lead to failing to execute the migration after too many iteration as the comment doesn't fit in storage any more.

To avoid that (and make it cleaner) I propose to replace the existing "Automatic Upgrade: " if present. or only add the prefix if the prefix is not already there.