Currently, the supported way (see GH#1922) to disable the default port
2222 port forward is:
config.vm.network :forwarded_port, guest: 22, host: 2222, disabled: true
However, the port collision detection runs on all ports, regardless of
the `disabled` flag. This leads it to attempt to connect to port
2222, notice it is taken, and abort with a port conflict -- even
though it will not be attempting to use the port at all.
Skip disabled ports when doing port conflict detection.
A workaround that does not require a Vagrant upgrade to one containing
this fix is to instead set `auto_correct` on the disabled port:
config.vm.network :forwarded_port, guest: 22, host: 2222, disabled: true, auto_correct: true
This allows the disabled port to be reshuffled off to some other
unused port.