[O] Setupfile doesn't seem to pass pre-defined macros

[emsenn]

Hey y'all,

I've recently been playing more with Org-mode's INCLUDE and SETUPFILE features, 
and think I might have found a bug.

File alpha.org contains

#+MACRO: womble fribble
#+AUTHOR: muffet

File beta.org contains

#+SETUPFILE: ./alpha.org
The womble macro is {{{womble}}}

File gamma.org contains

#+SETUPFILE: ./alpha.org
The author is {{{author}}}

---

Beta exports fine, but Gamma fails, saying: Undefined org macro: author; 
aborting

That seems like a bug to me, but am I misusing it? The manual's section on 
macro replacement says that author is among a few "pre-defined" macros: 
https://orgmode.org/manual/Macro-replacement.html

If I define author in a file, the macro work. If I INCLUDE Alpha it works too. 
But not if I use SETUPFILE.

Thanks for your time,
emsenn