run_script: fix PID file checking logic when the file is empty

This fixes issue #1075

I don't know why the elif explicitly negated the previous codnition, it's
obviously not needed because else if already implies the previous
condition is False.

Also, whoever added the parenthesis there messed up the logic even further,
before they were there, it worked okay, even if the condition was a bit
more verbose than logically needed. Well, that's what you get when you
blindly try to make code conform to PEP8 without actually reading it.

sopel/run_script.py

@@ -183,8 +183,7 @@ def main(argv=None):
                     else:
                         os.kill(old_pid, signal.SIGTERM)
                     sys.exit(0)
-            elif old_pid is None or (not tools.check_pid(old_pid)
-                                     and (opts.kill or opts.quit)):
+            elif opts.kill or opts.quit:
                 stderr('Sopel is not running!')
                 sys.exit(1)
         elif opts.quit or opts.kill: