[Cuis-dev] Fix for race condition in the Browser

[Luciano Notarfrancesco]

Running the base image tests with a browser open triggers an exception and
opens a debugger. This is a race condition that happens because there's a
process in the background adding and removing the
category '__Refactoring-TestData__' while the UI process calls the Browser
to update the category list. The attached changeset fixes it.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.cuis.st/mailman/archives/cuis-dev/attachments/20220501/df06d223/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Browser-systemCategoryRoots.st
Type: application/octet-stream
Size: 808 bytes
Desc: not available
URL: <http://lists.cuis.st/mailman/archives/cuis-dev/attachments/20220501/df06d223/attachment.obj>