Re: [PATCH v3 09/10] fetch: fetch unpopulated, changed submodules

A few tests added by this patch have been failing on one specific job (linux-gcc ubuntu-latest) at GitHub CI.

https://github.com/git/git/runs/5341052811?check_suite_focus=true#step:5:3968 https://github.com/git/git/runs/5343133021?check_suite_focus=true#step:4:5520

    Side note: you may need to be logged in to GitHub to view them.
    These two use different versions of CI to show the test traces;
    in the latter you may have to click on right-facing rectangle on
    the line with label "5520" to see the breakage.

I think there is some baked-in assumption in the failing test what the name of the initial branch by default is, which may be the reason why this particular job fails while others don't.

Can you take a look at it?

Thanks.