If slave pod keeps pending for some issue, it will still be pending after the issue is fixed:

1. Make node is unreachable;
2. Create pipeline build - slave pod will keep pending since no node available
3. Cancel the build
4. Fix the node issue
5. Start a new build

Actual results:
Build cannot finish since it is still using the pending slave pod.

Expected results:
Issued slave pod needs to be garbage collected.