Levente Uzonyi uploaded a new version of Collections to project The Trunk:
http://source.squeak.org/trunk/Collections-ul.463.mcz

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

Name: Collections-ul.463
Author: ul
Time: 4 October 2011, 8:25:51.321 pm
UUID: 2dda520b-035d-8a40-b62b-c285552d07ee
Ancestors: Collections-eem.462

- use #becomeForward: instead of #become:

=============== Diff against Collections-eem.462 ===============

Item was changed:
  ----- Method: CharacterSet>>add: (in category 'collection ops') -----
  add: aCharacter
  	"I automatically become a WideCharacterSet if you add a wide character to myself"
  	
  	aCharacter asciiValue >= 256
  		ifTrue: [| wide |
  			wide := WideCharacterSet new.
  			wide addAll: self.
  			wide add: aCharacter.
+ 			self becomeForward: wide.
- 			self become: wide.
  			^aCharacter].
  	map at: aCharacter asciiValue + 1 put: 1.
  	^aCharacter!

Item was changed:
  ----- Method: CharacterSetComplement>>removeAll (in category 'collection ops') -----
  removeAll
+ 
+ 	self becomeForward: CharacterSet new!
- 	| newSet |
- 	newSet := CharacterSet new.
- 	self become: newSet!

Item was changed:
  ----- Method: LookupKey>>beBindingOfType:announcing: (in category 'bindings') -----
  beBindingOfType: aClass announcing: aBool
  	"Make the receiver a global binding of the given type"
+ 
- 	| old new |
  	(Smalltalk globals associationAt: self key) == self
  		ifFalse:[^self error:'Not a global variable binding'].
  	self class == aClass ifTrue:[^self].
+ 	self becomeForward: (aClass key: self key value: self value).
- 	old := self.
- 	new := aClass key: self key value: self value.
- 	old become: new.
  	"NOTE: Now self == read-only (e.g., the new binding)"
  	^self recompileBindingsAnnouncing: aBool!