This restores Qubes R3.2 behavior
Before this patch, the following:
qvm-run -p sys-firewall 'echo -e "\e[0;46mcyan!" >&2' | wc -l
leaks the escape sequences through to the dom0 terminal via stderr,
in this case demonstrated by the ability to change the text color while
it should be fixed to red.
This can also be abused with xterm reporting sequences to cause input
to be sent to the dom0 terminal. This is potentially a security issue.
87230fc042