I have a change set that I'm copying into another change set.
I get a walkback when I do this.

In ClassChangeRecord>>assimilateAllChangesIn:, otherRecord looks like
this:

inForce: 	false
revertable: 	false
changeTypes: 	an IdentitySet(#rename #addedThenRemoved)
thisDefinition: 	nil
priorDefinition: 	'NCConstraintMorph subclass: #NCHandleConstraintMorph
	instanceVariableNames: ''''
	classVariableNames: ''''
	poolDictionaries: ''''
	category: ''NK-NewConnectors'''
thisName: 	#NCLabelConstraintMorph
priorName: 	#NCHandleConstraintMorph
thisOrganization: 	nil
priorOrganization: 	nil
thisComment: 	nil
priorComment: 	nil
thisMD: 	nil
priorMD: 	nil
methodChanges: 	an IdentityDictionary(#applyConstraint:->a
MethodChangeRecord (#change) #constrainedHasHalo->a MethodChangeRecord
(#change) #extent:->a MethodChangeRecord (#add) #initialize->a
MethodChangeRecord (#change) #offset->a MethodChangeRecord (#add)
#offset:->a MethodChangeRecord (#change) #position:->a
MethodChangeRecord (#change) #setOffset->a MethodChangeRecord (#change)
#setOffsetFrom:->a MethodChangeRecord (#change) #step->a
MethodChangeRecord (#add) #visible->a MethodChangeRecord (#add)
#wantsSteps->a MethodChangeRecord (#remove) )


Image version: Squeak3.1alpha of 7 February 2001
latest update: #3737
Current Change Set: NewConnectors-nk

VM version: Squeak3.0 of 4 February 2001 [latest update: #3446]
for: unix

Receiver: a ClassChangeRecord

Instance variables: 
inForce: 	false
revertable: 	false
changeTypes: 	an IdentitySet(#rename)
thisDefinition: 	nil
priorDefinition: 	nil
thisName: 	#NCLabelConstraintMorph
priorName: 	'NCHandleConstraintMorph'
thisOrganization: 	nil
priorOrganization: 	nil
thisComment: 	nil
priorComment: 	nil
thisMD: 	nil
priorMD: 	nil
methodChanges: 	an IdentityDictionary()

Method (temp) variables: 
changeSymbol: 	#addedThenRemoved
class: 	nil

Stack: 
ClassChangeRecord(Object)>>error:
ClassChangeRecord>>noteChangeType:fromClass:
[] in ClassChangeRecord>>assimilateAllChangesIn:
IdentitySet(Set)>>do:
ClassChangeRecord>>assimilateAllChangesIn:
ChangeSet>>absorbClass:from:
[] in ChangeSet>>assimilateAllChangesFoundIn:
SortedCollection(OrderedCollection)>>do:
ChangeSet>>assimilateAllChangesFoundIn:
ChangeSorter>>copyAllToOther
ChangeSorter(StringHolder)>>perform:orSendTo:
[] in MenuItemMorph>>invokeWithEvent:
BlockContext>>ensure:
CursorWithMask(Cursor)>>showWhile:
MenuItemMorph>>invokeWithEvent:
MenuItemMorph>>mouseUp:
MenuItemMorph>>handleMouseUp:
MouseButtonEvent>>sentTo:
MenuItemMorph(Morph)>>handleEvent:
MorphicEventDispatcher>>dispatchDefault:with: