the nginx-cfg file under tmp part will not be cleaned up

[hchenxa]

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Is this a BUG REPORT or FEATURE REQUEST? (choose one):

NGINX Ingress controller version:
0.19.0

Kubernetes version (use kubectl version):
v1.11.1

Environment:

• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Others:

What happened:

before apply the change of nginx, the nginx ingress controller have logic to generate a tmp file which used for nginx test with nginx -t, so if some ingress resource have bad configuration to failed pass the test, the tem file will not have change to delete, so it will generate so many tmp file like below:

root@nginx-ingress-controller-lqd4j:/tmp# ls -lrt | grep nginx-cfg | wc -l
4952

from above info, we can see that have about 5000 files generated.

What you expected to happen:

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know: