Searching through their github, I see no mention of python:2 dependency. The only place python is mentioned is that it will need pygobject3, (dev-python/pygobject:3) which does not hard depend on python:2 A naive build of harfbuzz with PYTHON_COMPAT=( python3_6 ) succeeds.
from my also naive point of view it seems that the ebuild needs python only for running tests. have you tried if these tests also work with python3*, instead of python2_7?
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=af921aeec86e284b92c3a3942a936d7ac13283cc commit af921aeec86e284b92c3a3942a936d7ac13283cc Author: Lars Wendler <polynomial-c@gentoo.org> AuthorDate: 2020-01-14 09:20:45 +0000 Commit: Lars Wendler <polynomial-c@gentoo.org> CommitDate: 2020-01-14 09:21:01 +0000 media-libs/harfbuzz: Allow python3 for tests as well Closes: https://bugs.gentoo.org/705378 Package-Manager: Portage-2.3.84, Repoman-2.3.20 Signed-off-by: Lars Wendler <polynomial-c@gentoo.org> media-libs/harfbuzz/harfbuzz-2.6.4.ebuild | 4 ++-- media-libs/harfbuzz/harfbuzz-9999.ebuild | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-)