[py-dev] distributed test slave activation of external plugin

[meme dough]

Hi,

Is there any way to activate external plugins for distributed testing
on the slave side?

Currently pytest-cov requires that it is installed on the slave
version of python.  This differs from pytest-xdist that will rsync
itself across, such that the only requirement on the slave side is
python.

If pytest-cov is not installed on the slave then the master has sent
the slaveinput but the plugin is never activated on the slave hence no
coverage.

I can rsync pytest-cov over to the slave in same way as py / xdist
already get done but unknown if I can activate the plugin.

A separate but related issue:  It would be good to have some way (cmd
line / conftest / api) to tell xdist not to rsync py / xdist to the
slave.  The case is needed for the client code where it take care of
all rsync so second rsync by xdist produce the warning about to two py
and two xdist on path.

:)