When stopping wpa_supplicant, the code is supposed to check if a file named $PIDFILE exists and kill the process listed inside. Instead it was checking if a directory named $PIDFILE exists and because this was never the case, killing of the wpa_supplicant process would always silently fail.
This would, after a few invocations of the ifup command, leave the system with large number of running wpa_supplicant processes, all trying to take control of the same interface.
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