>> Thanks.  Here is the updated patch.  I tested it with minibuffer-only 
>> frames, and it seems to work.
>>
>> Are you sure that it's okay to rebind M-c in 
>> minibuffer-local-completion-map?  It's a good mnemonic for 
>> "completion", but it hides the capitalize-word binding, that users 
>> might possibly want to use there (I don't, it's only when thinking 
>> about this patch that I realized this).
>>
>> Another option would be M-g, which would not hide anything that is 
>> possibly useful in the minibuffer, and is still a mnemonic of "goto".
>
> Thanks; applied to Emacs 28.
>
> I went with `M-g' -- it seems pretty natural here.  If anybody else 
> wants a different key binding, go ahead and change it.
>

Juri said recently that he uses some of the keys in M-g in the minibuffer, 
so I changed my mind, and I now think that it would be better to use 'M-g 
M-c' for this, which is unused, and does not hide the complete M-g map. 
Updated patch attached.  WDYT?