Field.stop_words is overwritten and is no longer a set

[artemisart]

text/torchtext/data/field.py

Lines 166 to 173 in 758d356

	if stop_words is not None:
	try:
	self.stop_words = set(stop_words)
	except TypeError:
	raise ValueError("Stop words must be convertible to a set")
	else:
	self.stop_words = stop_words
	self.stop_words = stop_words

I think this is an error and self.stop_words should not be overwritten after the condition.