It "works": it returns an array of type object when the arguments are not all 1-D arrays of the same size.  The description of the return value in the docstring explains this, and that's what happens in the example in the docstring, but it is hidden by the immediate unpacking into `ta` and `tb`.

This is how it worked before this PR.  I'm not too fond of it--I think returning a list would be fine.  But technically, that is an API change.