It appears we're getting the correct output, but in the wrong order,
so pexpect doesn't filter it correctly:
> \r\n\x1b]133;C;cmdline_url=echo%20bar\x07bar\r\n\x1b]133;D;0\x07\x1b[?25h⏎ \r⏎ \r\rprompt 39>\x1b[?2004h
That `\x07bar` should be the \a that marks the end of the escape
sequence, followed by the actual "bar", followed by sequences marking
the end of output...