How about use traceback to print the stack?
import numpy as np
def err_handler(type, flag):
import traceback
traceback.print_stack(limit=2)
print "Floating point error (%s), with flag %s" % (type, flag)
saved_handler = np.seterrcall(err_handler)
save_err = np.seterr(all='call')
a = np.array([1, 2, 3])
b = 0.0
a / b