Use the well known (x ifNil: [...]) idiom rather than the longer (x ifNotNil: [:y | y] ifNil: [...])
=============== Diff against System-ul.1032 ===============
Item was changed:
----- Method: ChangeSet class>>assuredChangeSetNamed: (in category 'services') -----
"Answer a change set of the given name. If one already exists, answer that, else create a new one and answer it."