A new version of Collections was added to project The Inbox:
http://source.squeak.org/inbox/Collections-ael.481.mcz

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

Name: Collections-ael.481
Author: ael
Time: 30 July 2012, 2:40:08.671 pm
UUID: c2a7afc0-37ac-404b-ae81-bf782e1dd254
Ancestors: Collections-cwp.480

remove spurious sharing of associations between a dictionary and another created from it

=============== Diff against Collections-cwp.480 ===============

Item was changed:
  ----- Method: Dictionary class>>newFrom: (in category 'instance creation') -----
  newFrom: aDict 
  	"Answer an instance of me containing the same associations as aDict.
  	 Error if any key appears twice."
  	| newDictionary |
  	newDictionary := self new: aDict size.
  	aDict associationsDo:
  		[:x |
  		(newDictionary includesKey: x key)
  			ifTrue: [self error: 'Duplicate key: ', x key printString]
+ 			ifFalse: [newDictionary add: x copy]].
- 			ifFalse: [newDictionary add: x]].
  	^ newDictionary
  
  "	NewDictionary newFrom: {1->#a. 2->#b. 3->#c}
  	{1->#a. 2->#b. 3->#c} as: NewDictionary
  	NewDictionary newFrom: {1->#a. 2->#b. 1->#c}
  	{1->#a. 2->#b. 1->#c} as: NewDictionary
  "!