kill-old-processes is picking up httpd processes, which shouldn't be happening because we should be tearing down these processes when we teardown the http server in webkitpy.
Not convinced this is a general problem, looking through buildbot logs, I could only find one example of httpd staying around after run-webkit-tests finished.
I don't think we actually want to do this one. <https://ews-build.webkit.org/#/builders/24/builds/5390/steps/14/logs/stdio> Marking this bug as 'won't fix'