Sometimes "adb devices" will return phantom Android emulator instances

[antoinevg]

Sometimes when running:

adb devices -l

…the list of emulators returned will contain one or more devices that do not exist.

This can happen because:

1. adb scans the local network interface for open ports in the range 5xxx to 6xxx.
2. If it finds an open port it does not verify that it actually belongs to an android emulator

A good way to track this down on the mac is to run something like:

sudo lsof -PiTCP -sTCP:LISTEN

…and check for processes with open ports in that range