[IMPR] re-use throttle PID (Step 1)
[IMPR] re-use throttle PID (Step 1)

After dropping a throttle PID it can be reused for a next process.
PID (Process IDentifier) is to be used for logging filenames to
prevent WindowsError/PermissionError if runnng more than one script
with the same name.

Bug: T56685
Change-Id: I7588e81c15c77b63fe919c653a33430f71f5c538

wikimedia/pywikibot-core,wikimedia/pywikibot-core