Code review comment for ~ltrager/maas:emulate_terminal

How does this fix progress bars or spinners? Some progress bars are dots with a percentage as show in the bug, but some might use # signs etc. Additionally, spinners, when spinning will show hyphens '-' while the spinner is spinning between backslash-hyphen-forwardslash and so forth. Is this branch to fix all those possibilities or are we just doing it for the carriage return and backslash like you have in your code?