sterm randomly? chooses serial port

[ConradBraam]

When I have more than one target connected, the sterm command does not use my selected target's port, it seems to choose alphabetically.

mbed sterm --baudrate 115200
Will often just connect to the "other" target even though I did set the target.
mbed config target NUCLEO_F401RE
This config should tell the sterm component in the toolchain to use the desired target if I have 2 targets, in my case namely:
mbedls
DISCO_L475VG_IOT01A[0] | E: | COM18
NUCLEO_F401RE[0] | D: | COM15

A note: supplying a -m flag to the command gets ignored/not parsed; a separate class of problem, but might just be fixable in a single ticket.

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-192

[screamerbg]

I'll put up a PR to address this.

[adbridge]

Apologies, this was closed in error by the automated bot - re-opening.