The problem appears to be confined to the scenario where the *only* specified console is a USB device:
# FAILS (when cmdline ends with):
console=ttyUSB0,115200n8r console=ttyUSB0,115200 console=ttyUSB0 console=ttyUSB0,115200n8r debug
# WORKS (when cmdline ends with):
console=ttyUSB0 console=tty console=tty console=ttyUSB0
(The bug title needs to be changed to reflect this).
The problem appears to be confined to the scenario where the *only* specified console is a USB device:
# FAILS (when cmdline ends with):
console= ttyUSB0, 115200n8r ttyUSB0, 115200 ttyUSB0, 115200n8r debug
console=
console=ttyUSB0
console=
# WORKS (when cmdline ends with):
console=ttyUSB0 console=tty
console=tty console=ttyUSB0
(The bug title needs to be changed to reflect this).