See https://github.com/git/git/commit/8959555cee7ec045958f9b6dd62e541affb7e7d9

This fixes default packet redirection when merging multiple re6st
networks. Nodes will then install multiple default routes for each re6st
network with the correspond src-prefix.

The changes include:

- redistribute default route with src prefix on gateways
- remove the now obsolete default option
- if subtrees is not available in the kernel, delete src prefix from
  the default route and don't advertise the default route to other
  nodes
- if there is no src prefix in the redistributed default route, add
  one to be retro-compatible with the old gateway behaviour

Implement select in multicast.py to fix immediate return causing 100% cpu load
See merge request !39

This reverts commit f9b112a7

python-unshare and python-passfd are dependencies of nemu: https://github.com/NightTsarina/nemu/blob/master/setup.py#L18,
but nemu in pypi: https://pypi.org/project/nemu/0.3.1/ is outdated, it has no dependency defined
so keep those here

This is required for 47f69a00
("redistribute default routes with src-prefix").

See merge request !38

For instance 89.30.119.100 has an entry in the geoip2 database without country
key

anyway, let test failed if any error

modify fixnemu device name comment, remove extra line, space, remove dup
definition, eek

Remove duplicate definitions of DEMO_DIR, and define it in the tests
module