[O] FILETAGS tags hidden by TAGS option

[Mark Edgington]

When using org-tags-view, the list of tags used for tab-completion
fails to include tags specified via the #+FILETAGS option when there
exists a #+TAGS option in the file which doesn't contain the
#+FILETAGS tags.

For example, with the following options, the foo tag will not show up
when trying to do tab-completion, but only bar and baz will:

#+TAGS:  bar baz
#+FILETAGS:  foo

Is this the expected behavior?  A "workaround" is to simply add foo to
#+TAGS, but should this be necessary?