The ordinal range 0x80-0x9F is the C1 control code set [1]. Ordinal 0x9F is "Application Program Command" (APC). The command must be terminated by ordinal 0x9C, "String Terminator" (ST). For example, "\x9f Some Command \x9c". 

In Gnome Terminal, after executing print('\x9f'), an APC command without a terminator, typing Ctrl+L still works to clear the screen and get back to a prompt.

[1] https://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_controls