>>>>> I'm compiling Emacs master right now (on macOS Catalina) and have 
>>>>> detected a couple of warnings 'assignment to free variable 
>>>>> repeat-map' (one in tab-bar.el and one in window.el) Which I haven't 
>>>>> seen before...
>>>> 
>>>> I don't see any warnings, so please show the warnings you see.
>>> 
>>> I see them (and have seen them for a week or two), too:
>>> 
>>> In toplevel form: tab-bar.el:2093:33: Warning: assignment to free 
>>> variable ‘repeat-map’ In toplevel form: window.el:10261:33: Warning: 
>>> assignment to free variable ‘repeat-map’
>> 
>> Isn't this just the usual case of a stale lisp/ldefs-boot.el?  IOW, I'd 
>> expect the warnings to go away when that file is updated to include the 
>> repeat-map autoload.
>
> I don't know, but I don't think that's the cause.  What I do know is 
> that these warnings are displayed when running "make -j" on a fresh 
> clone of the repository.
>

Hmmm...  In fact you're correct: the autoloaded repeat-map is not added to 
ldefs-boot.el.  I have no idea why.