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Prevent weirds unicode messages from being displayed in TTYs.

Libvirtd version 0.8.8 is capable of handling connections to virtio consoles but
the Python API is broken.

Opening stdout/stderr in write mode to prevent exceptions to be raised.

The version fixes bug related to SIGCHLD handling in libev, this is needed some
cc-node functionalities to work (live migrations).

Tunnel endpoints are now automaticaly closed by default.

It uses pyev child watcher to handles child termination instead of calling
waitpid.