[bug] stop sandbox failed for not finding network namespace path

[YaoZengzeng]

Ⅰ. Issue Description

When I'm doing node-e2e test for Pouch CRI, there are lot of log like:

ERRO[2018-06-15 06:57:18.160883152] Error deleting network: failed to Statfs "/proc/10435/ns/net": no such file or directory 
ERRO[2018-06-15 06:57:18.160936276] StopPodSandbox for "0ad2446f4a41ad160ac10b59a3efeb81a284a955decbee74cb37750d5a303073" failed, error: failed to destroy network for sandbox "0ad2446f4a41ad160ac10b59a3efeb81a284a955decbee74cb37750d5a303073": failed to Statfs "/proc/10435/ns/net": no such file or directory 

That means the pod can't be stopped because of the pod network can't be teared down.

However through pouch ps -a, the corresponding container has been stopped, so we can't find the corresponding network namespace obviously and we won't stop the sandbox successfully forever.

So I need to configure now whether kubelet will stop sandbox multiple times, if it is true, we need to change the logic of StopSandbox in CRI manager.