Description of problem:
Deprecate old cold merge verb
Code change only; nothing to verify
So hosts with 4.0 VDSM would still work? What is 'old' cold merge verb? How old is it?
Absolutely, hosts with 4.0 Vdsm will use the 'old' flow (introduced in 3.1). The fact that we are marking the verb as deprecated doesn't mean that we are removing it, this only states that the API will be removed in a future version.
In a nutshell, the 'old' cold was done using a single SPM verb (that we are marking as deprecated now) where the data copied from base volume to top volume (hence the low performance when base is large and top is small).
Move to VERIFIED based on comment1 and explanation in comment3
New Cold merge has been tested