[O] Globally set categories overwhelm tree inheritance

[William Léchelle]

Happy new year list :)

Constructing a custom agenda using (org-entry-get (point) "CATEGORY" t) in an
org-agenda-skip-function, I found a rare case of strangely inherited property,
when a #+Category:foo line is present (at the top of the file) :

If an entry has no property drawer, it correctly inherits its CATEGORY property
from its hierarchy, but if it *has* one, *not* featuring a category property,
then the #+Category one supersedes that of the entry's hierarchy.

I know #+Category is obsolete, and for subtree-category differentiation
properties are the way to go, but I thought of it as a file-local fallback
value, and apparently it's not reliable for this either, as it infringes
inheritance logic when property drawers are present.

Reporting just in case someone else still uses #+Category and bumps into it.