Fabio Niephaus uploaded a new version of ReleaseBuilder to project The Trunk:
http://source.squeak.org/trunk/ReleaseBuilder-fn.205.mcz

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

Name: ReleaseBuilder-fn.205
Author: fn
Time: 25 February 2020, 3:28:27.155422 pm
UUID: 58d377fb-0bb4-4d83-b03d-2febf2e4b6fe
Ancestors: ReleaseBuilder-mt.204

Bump the image version to Squeak5.3rc1.

=============== Diff against ReleaseBuilder-mt.204 ===============

Item was changed:
  ----- Method: ReleaseBuilder class>>initialize (in category 'class initialization') -----
  initialize
  
  	QAndA ifNil: [self clearQAndA].
  
  	"We have to be after AutoStart so that Morphic is up and running."
  	Smalltalk addToStartUpList: ReleaseBuilder after: AutoStart.
  
+ 	SystemVersion newVersion: 'Squeak5.3rc1'!
- 	SystemVersion newVersion: 'Squeak5.3beta'!