Perforce is inconsistent with the casing in filespec status messages that the server returns.

As an example, different teams that I work with have seen p4 merge commands return the following messages depending on the p4 server version and/or merge options provides.

all revision(s) already integrated.
All revision(s) already integrated.

It would be simple to update the Validate#check method to lowercase both the filespec status messages and messages in the ignore list.