Fix the error in building tc commands (#865)

[ti-srebot]

cherry-pick #865 to release-0.9

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Signed-off-by: Yang Keao keao.yang@yahoo.com

What problem does this PR solve?

2020-09-02T03:47:24.659Z        INFO    chaos-daemon-server     build command   {"command": "nsenter -n/proc/20669/ns/net -- tc qdisc add dev eth0 parent 1: handle 2: netem  duplicate 80.000000 25.000000"}
2020-09-02T03:47:24.685Z        ERROR   chaos-daemon-server     error while adding tc   {"error": "error code: exit status 1, msg: Illegal \"limit\"\n"}

There is an extra space between "netem" and "duplicate" (which will lead to an "" in args).

BTW: What is the best practice of concating command line arguments? Directly working on a []string seems too complicated (as I will need to convert integer/float to string everywhere).

What is changed and how does it work?

Checklist

Tests

• Unit test

[ti-srebot]

/run-all-tests

[cwen0]

/merge

[ti-srebot]

Sorry @cwen0, you don't have permission to trigger auto merge event on this branch.