In a fresh Squeak 3.7b 5878 image if I try to rename a class it works as
expected. Same fresh image, but after installing Monticello v150 from
SqueakMap if I try to rename a class I got this walkback.

21 April 2004 10:33:27 am

VM: Win32 - a SmalltalkImage
Image: Squeak3.7beta [latest update: #5878]

SecurityManager state:
Restricted: false
FileAccess: true
SocketAccess: true
Working Dir C:\Squeak\Squeak-Tesis
Trusted Dir C:\Squeak\Squeak-Tesis\guru
Untrusted Dir C:\My Squeak\guru

UndefinedObject(Object)>>doesNotUnderstand: #beginsWith:
	Receiver: nil
	Arguments and temporary variables: 
		aMessage: 	beginsWith: 'Compiler-'
	Receiver's instance variables: 
nil

PackageInfo>>category:matches:
	Receiver: a PackageInfo
	Arguments and temporary variables: 
		categoryName: 	nil
		prefix: 	'Compiler'
	Receiver's instance variables: 
		packageName: 	'Compiler'
		methodCategoryPrefix: 	nil

PackageInfo>>includesSystemCategory:
	Receiver: a PackageInfo
	Arguments and temporary variables: 
		categoryName: 	nil
	Receiver's instance variables: 
		packageName: 	'Compiler'
		methodCategoryPrefix: 	nil

PackageInfo>>includesClass:
	Receiver: a PackageInfo
	Arguments and temporary variables: 
		aClass: 	ClockMorph
	Receiver's instance variables: 
		packageName: 	'Compiler'
		methodCategoryPrefix: 	nil


--- The full stack ---
UndefinedObject(Object)>>doesNotUnderstand: #beginsWith:
PackageInfo>>category:matches:
PackageInfo>>includesSystemCategory:
PackageInfo>>includesClass:
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
MCWorkingCopy(MCPackageManager)>>classModified:
WeakMessageSend>>valueWithArguments:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[answer := each valueWithArguments: anArray]}
BlockContext>>on:do:
WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[:exc |  self valueWithArguments: anArray startingFrom: index + 1.  exc
pass]}
BlockContext>>valueWithPossibleArgs:
[] in MethodContext(ContextPart)>>handleSignal: {[(self tempAt: 2)  
valueWithPossibleArgs: {exception}]}
BlockContext>>ensure:
MethodContext(ContextPart)>>handleSignal:
MessageNotUnderstood(Exception)>>signal
UndefinedObject(Object)>>doesNotUnderstand: #beginsWith:
PackageInfo>>category:matches:
PackageInfo>>includesSystemCategory:
PackageInfo>>includesClass:
MCWorkingCopy(MCPackageManager)>>classModified:
WeakMessageSend>>valueWithArguments:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[answer := each valueWithArguments: anArray]}
BlockContext>>on:do:
WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[:exc |  self valueWithArguments: anArray startingFrom: index + 1.  exc
pass]}
BlockContext>>valueWithPossibleArgs:
[] in MethodContext(ContextPart)>>handleSignal: {[(self tempAt: 2)  
valueWithPossibleArgs: {exception}]}
BlockContext>>ensure:
MethodContext(ContextPart)>>handleSignal:
MessageNotUnderstood(Exception)>>signal
UndefinedObject(Object)>>doesNotUnderstand: #beginsWith:
PackageInfo>>category:matches:
PackageInfo>>includesSystemCategory:
PackageInfo>>includesClass:
MCWorkingCopy(MCPackageManager)>>classModified:
WeakMessageSend>>valueWithArguments:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[answer := each valueWithArguments: anArray]}
BlockContext>>on:do:
WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[:exc |  self valueWithArguments: anArray startingFrom: index + 1.  exc
pass]}
BlockContext>>valueWithPossibleArgs:
[] in MethodContext(ContextPart)>>handleSignal: {[(self tempAt: 2)  
valueWithPossibleArgs: {exception}]}
BlockContext>>ensure:
MethodContext(ContextPart)>>handleSignal:
MessageNotUnderstood(Exception)>>signal
UndefinedObject(Object)>>doesNotUnderstand: #beginsWith:
PackageInfo>>category:matches:
PackageInfo>>includesSystemCategory:
PackageInfo>>includesClass:
MCWorkingCopy(MCPackageManager)>>classModified:
WeakMessageSend>>valueWithArguments:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[answer := each valueWithArguments: anArray]}
BlockContext>>on:do:
WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
[] in WeakActionSequenceTrappingErrors>>valueWithArguments:startingFrom:
{[:exc |  self valueWithArguments: anArray startingFrom: index + 1.  exc
pass]}
...etc...