Hi Christian, Thanks for reporting this and providing a fix!
> The function `org-babel-python-evaluate-session' doesn't process temp > file names with `org-babel-process-file-name' before inserting them into > the Python code blocks. This causes a 'No such file' error when the > executing the code blocks on a remote directory. I tested this out and was able to reproduce the bug. > The attached patch fixes this issue, allowing compilation of Python > source blocks with a remote directory, such as :dir /ssh:user@server:/. I tested your patch and it solves the problem. > This is my first patch ever, so please let me know if there's ways I can > improve. The patch is pretty simple and I see no problems with it. Since it is so small, FSF copyright assignment shouldn't be necessary. Also, it looks like you followed all the guidelines on https://orgmode.org/worg/org-contribute.html. I'm fairly novice myself so will wait a couple days in case one of the more experienced folks notices any issues here. But I'll merge this to master by end of week if I don't hear anything.