I think that the GitPython commit is causing a corruption of this file:
.git/logs/refs/heads/pr-cmd-raise-with-stderr-on-error

I think it is supposed to be 1 line per commit with the first line of the commit at the end.
But I have all of the log message in the file that GitPython attempts to parse and errors out on.

Attached in the full file.

pr-cmd-raise-with-stderr-on-error.txt