The interaction with snap-recovery-chooser happens over stdin/stdout. The early
setup code in console-conf will attempt to restore sys.stdin/sys.stdout and hook
them up to the current tty.
The patch allows passing input/output streams explicitly as parameters to the
constructors.
Also, default to sys.stdin/sys.stdout and pass both streams explicitly when
constructing urwid.raw_display.Screen(), to workaround the bug in their
constructor. THe constructor is defined as follows:
class Screen(BaseScreen, RealTerminal):
def __init__(self, input=sys.stdin, output=sys.stdout):
What means, that even if we override sys.stdout/sys.stdin globally in our setup
code, this will have no effect as `input` and `output` already got their values.
Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
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