3.2.0, and osgearth's requirement was 3.0.1, to avoid conflicts with
other ports that depend on graphics/osg.
Make the graphics/osg version a variable, to ease maintainer's jobs as
graphics/osg gets updated (which requires osgearth's PORTREVISION and
PLIST_SUB to be bumped).
Some part of the discussion around PLIST_SUB is not recorded in the PR,
but it is still related to
PR: ports/184706
Submitted by: amdmi3
5a9ce54d8f