Others have reported this and it is extremely annoying.

The problem is caused by ExtensionWizard, which calls import git, which in turns tries to run git version. This would expect to fail when git is not installed, but MacOS tries to be smart and shows a dialog box to the user(!) to install stuff. I guess this behavior on Mac will be fixed, but until then we should be able to move out all the import git calls from ExtensionWizard initialization steps. I'll commit a fix soon.

I suspected that was the reason!

How about disabling that module by default, and only showing it when "Developer mode" is enabled? This would be a very harmless and effective fix, IMHO.

It could be a good option, too, but there is no mechanism implemented yet for disabling certain modules when developer mode is disabled. I've now changed ExtensionWizard to call import git only when git it is actually needed. I already have a fix, just wait for a build to complete to confirm it all works well.

Ah, I see. I thought there was a mechanism, since it is possible to disable tests when not in dev mode. But your solution makes total sense. Thank you for fixing it!

Fix committed r27535