Clean up ChangeOps related validation code

This is a direct follow-up to my comments in patch
I3778f7b4d9a212e7c6a83b3b156da8c1b64ccdf0.

I'm aware that I probably need to rebase this multiple times. ;-)

Change-Id: Iaa1d4774487ac9bc4397dea536e12c4337f6ebcb
Merge "Clean up ChangeOps related validation code"