The new --set-trusted-host option needs a new devpi-common release.
Because we dropped Python 2.6 support in devpi-common, we would either
have to backport the changes to devpi-common 2.x, or drop support of
Python 2.6 for devpi-client.
I vote for dropping Python 2.6 support. Soon pip will stop supporting it
and that will mean it will become even harder to test with Python 2.6.
Anyone who still needs Python 2.6 support should use an older
devpi-client release. All other devpi packages dropped Python 2.6
The next devpi-client release would then be 3.0.0.