Case-folding is locale-dependent
(See, for example,
and is enormously complicated.  We do not want to go there.

I suppose it does make sense to issue warnings if fossil detects
possible conflicts in filenames.  This can be done easily enough
for ASCII.  But because the problem is all but unsolvable for full
unicode, the change should be to add warnings only, and then only
for ASCII.  Some users may actually want to store files whose names
differ only in case and we don't want to have to go through all of
the complication to try to figure out unicode case folding.

I am changing this ticket to a feature request.