Scrapy spider never stops after stop attempt

[nicolasassi]

Describe the bug
The stop spider never actually stops the spider. It attempts to stop it, but the spider keeps on going until it finishes or the container is shut down

To Reproduce
Steps to reproduce the behavior:

1. start a scrapy spider
2. try to stop it using the stop button

Expected behavior
I would expect it would gracefully stop the spider.

Screenshots
If applicable, add screenshots to help explain your problem.