While running an apt upgrade I noticed:

/usr/lib/python3/dist-packages/pyqtgraph/examples/SpinBox.py:38: SyntaxWarning: invalid escape sequence '\$'
  regex='\$?(?P<number>(-?\d+(\.\d+)?)|(-?\.\d+))$')),

The \$ should be written \\$ or r'\$' since a few Python releases (same for all backslash escape that have no meanings). I don't have the time to search for other occurrences of this fact, but running the tests with PYTHONDEVMODE=1 should help spotting them :)