Nicolas Cellier uploaded a new version of Kernel to project The Trunk:
http://source.squeak.org/trunk/Kernel-nice.1328.mcz

==================== Summary ====================

Name: Kernel-nice.1328
Author: nice
Time: 10 May 2020, 6:37:59.503017 pm
UUID: 0dc2dc8d-e20b-4b2b-9db6-8c5ceacb165f
Ancestors: Kernel-nice.1327

Return to a safer ClassBuilder.

=============== Diff against Kernel-nice.1327 ===============

Item was changed:
  ----- Method: ClassBuilder>>name:inEnvironment:subclassOf:type:instanceVariableNames:classVariableNames:poolDictionaries:category: (in category 'class definition') -----
  name: className inEnvironment: env subclassOf: newSuper type: type instanceVariableNames: instVarString classVariableNames: classVarString poolDictionaries: poolString category: category
  	"Define a new class in the given environment"
  	^self 
  		name: className 
  		inEnvironment: env 
  		subclassOf: newSuper 
  		type: type 
  		instanceVariableNames: instVarString 
  		classVariableNames: classVarString 
  		poolDictionaries: poolString 
  		category: category
+ 		unsafe: false!
- 		unsafe: true!