How to get a traceback for Python warnings
import traceback
import warnings
import sys
def warn_with_traceback(message, category, filename, lineno, file=None, line=None):
log = file if hasattr(file, "write") else sys.stderr
traceback.print_stack(file=log)
log.write(warnings.formatwarning(message, category, filename, lineno, line))
warnings.showwarning = warn_with_traceback