Chris Muller uploaded a new version of Installer-Core to project The Inbox:
http://source.squeak.org/inbox/Installer-Core-cmm.429.mcz

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

Name: Installer-Core-cmm.429
Author: cmm
Time: 8 April 2019, 2:01:23.400753 pm
UUID: 12e11ef9-421b-4e4c-88b0-a4921fe4d4a8
Ancestors: Installer-Core-tcj.426

Allow installation of github projects via the scripts at the top of their readme files, without first having to manually ensure Metacello is installed.

	Metacello new
		baseline: 'NameOfTheProject';
		repository: 'github://...';
		load

=============== Diff against Installer-Core-tcj.426 ===============

Item was changed:
  ----- Method: Installer class>>ensureRecentMetacello (in category 'scripts') -----
  ensureRecentMetacello
  	"Copied and adapted from https://github.com/Metacello/metacello/blob/master/README.md"
  	
  	| metacello |
  	((Smalltalk classNamed: #WebClient)
  		ifNil: [ false ]
  		ifNotNil: [ :webClient | 
  			[ (webClient httpHead: 'https://github.com') isSuccess ] 
  				on: Error
  				do: [ false ] ])
  		ifFalse: [ ^self inform: 'Could not connect to "https://github.com".\\You need an internet connection and SSL support\to install (or update) Metacello.\\Please fix those issues and try again.' translated withCRs ].
  	
+ 	"Squeak is shipped with the global #Metacello referring to lightweight MetacelloStub.  After the first message is sent, the latest Metacello is installed, replacing the stub."
+ 	metacello := Smalltalk at: #Metacello.
+ 	metacello = MetacelloStub ifTrue: [
- 	metacello := (Smalltalk classNamed: #Metacello) ifNil: [
  		"Get the Metacello configuration (for Squeak users)"
  		Installer gemsource
  			project: 'metacello';
  			addPackage: 'ConfigurationOfMetacello';
  			install.
  
  		"Bootstrap Metacello Preview, using mcz files (#'previewBootstrap' symbolic version"
  		((Smalltalk classNamed: #ConfigurationOfMetacello) project 
  			version: #'previewBootstrap') load.
  
  		Smalltalk classNamed: #Metacello ].
  
  	"Now load latest version of Metacello"
  	metacello new
  		baseline: 'Metacello';
  		repository: 'github://Metacello/metacello:master/repository';
  		get.
  	metacello new
  		baseline: 'Metacello';
  		repository: 'github://Metacello/metacello:master/repository';
  		load: #('default' 'Metacello-Help').
  !

Item was added:
+ Object subclass: #MetacelloStub
+ 	instanceVariableNames: ''
+ 	classVariableNames: ''
+ 	poolDictionaries: ''
+ 	category: 'Installer-Core'!
+ 
+ !MetacelloStub commentStamp: 'cmm 4/8/2019 14:00' prior: 0!
+ MetacelloStub is a loose reference to the class Metacello in its host repository.  It's kept at both its real name, #MetacelloStub, as well as the name #Metacello.  This is done to allow Squeak to respond to messages sent to Metacello (e.g., as referenced in external installation scripts), without the need to ship with Metacello pre-installed.!

Item was added:
+ ----- Method: MetacelloStub class>>doesNotUnderstand: (in category 'overriding') -----
+ doesNotUnderstand: aMessage 
+ 	(UIManager confirm: 'This action requires Metacello, but it''s not installed.  Download and install it now?') ifTrue:
+ 		[ Installer ensureRecentMetacello.
+ 		^ aMessage sentTo: (Smalltalk classNamed: #Metacello) ]!

Item was added:
+ ----- Method: MetacelloStub class>>initialize (in category 'initialize-release') -----
+ initialize
+ 	Smalltalk
+ 		at: #Metacello
+ 		ifAbsentPut: [ self ]!