Fix Fetch progress bar by fvalette-ledger · Pull Request #1971 · gitpython-developers/GitPython

See gitpython-developers#1969

stderr parser call RemoteProgress update on each line received.
With universal_newlines set to False, there is a mixup between
line feed and carriage return.
In the `handle_process_output` thread, this is thus seen as a single
line for the whole output on each steps.

This should be undone once python 3.7 is EOL.