extract-archive: don't fail on chown pxemngr files

This patch will need to be reverted after I.1.2.0 release, since we
don't want to fail when chown pxemngr files.
It's because we did not have pxemngr on install-server before.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>