TL;DR:
I'd like to propose a change where packages should NOT install their
tests to ${D} by default. Such an install may optionally enabled with
USE=test, which should be decoupled from FEATURES=test. Or depending on
the color of the bikeshed, we add something new like USE=install-tests.

Background:
Python packages install a number of _test.py files, and related .pyc
files. The files are generally useful for running tests after the
package is installed, and may have additional testing dependencies that
are not installed via RDEPEND.

As an example, on the livegui install media, these files take 100MB+
before squashfs compression.

Some users MAY wish to verify that a package continues to function
correctly, and they should have the USE=test dependencies available at
runtime, and the tests installed.

Such post-install testing may also require other files to be present, to
configure the test suite runs.

-- 
Robin Hugh Johnson
Gentoo Linux: Dev, Infra Lead, Foundation President & Treasurer
E-Mail   : robbat2@gentoo.org
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