(org-table-make-reference): A range with only empty fields should lead
to length 0.
* testing/lisp/test-org-table.el: Adapt expected for several
ert-deftest.
The range len bugs may lead to wrong calculations for range references
with empty fields when the range len is relevant. Affects typically
Calc vmean on simple range and without format specifier EN. Also
Lisp with e. g. `length' on simple range or with L.
It is worth a small compatibility change: For a range with only empty
fields it is now possible and necessary to choose different behaviors
of vmean by adding the format specifiers E and/or N.
This is a follow-up of commit
764315b3fc.
5625a6ed79