hack for apparently broken parse_qs in python2

youtube_dl/utils.py

@@ -49,7 +49,81 @@ except ImportError: # Python 2
 try:
 	from urllib.parse import parse_qs as compat_parse_qs
 except ImportError: # Python 2
-	from urlparse import parse_qs as compat_parse_qs
+	# HACK: The following is the correct parse_qs implementation from cpython 3's stdlib.
+	# Python 2's version is apparently totally broken
+	def _unquote(string, encoding='utf-8', errors='replace'):
+		if string == '':
+			return string
+		res = string.split('%')
+		if len(res) == 1:
+			return string
+		if encoding is None:
+			encoding = 'utf-8'
+		if errors is None:
+			errors = 'replace'
+		# pct_sequence: contiguous sequence of percent-encoded bytes, decoded
+		pct_sequence = b''
+		string = res[0]
+		for item in res[1:]:
+			try:
+				if not item:
+					raise ValueError
+				pct_sequence += item[:2].decode('hex')
+				rest = item[2:]
+				if not rest:
+					# This segment was just a single percent-encoded character.
+					# May be part of a sequence of code units, so delay decoding.
+					# (Stored in pct_sequence).
+					continue
+			except ValueError:
+				rest = '%' + item
+			# Encountered non-percent-encoded characters. Flush the current
+			# pct_sequence.
+			string += pct_sequence.decode(encoding, errors) + rest
+			pct_sequence = b''
+		if pct_sequence:
+			# Flush the final pct_sequence
+			string += pct_sequence.decode(encoding, errors)
+		return string
+
+	def _parse_qsl(qs, keep_blank_values=False, strict_parsing=False,
+				encoding='utf-8', errors='replace'):
+		qs, _coerce_result = qs, unicode
+		pairs = [s2 for s1 in qs.split('&') for s2 in s1.split(';')]
+		r = []
+		for name_value in pairs:
+			if not name_value and not strict_parsing:
+				continue
+			nv = name_value.split('=', 1)
+			if len(nv) != 2:
+				if strict_parsing:
+					raise ValueError("bad query field: %r" % (name_value,))
+				# Handle case of a control-name with no equal sign
+				if keep_blank_values:
+					nv.append('')
+				else:
+					continue
+			if len(nv[1]) or keep_blank_values:
+				name = nv[0].replace('+', ' ')
+				name = _unquote(name, encoding=encoding, errors=errors)
+				name = _coerce_result(name)
+				value = nv[1].replace('+', ' ')
+				value = _unquote(value, encoding=encoding, errors=errors)
+				value = _coerce_result(value)
+				r.append((name, value))
+		return r
+
+	def compat_parse_qs(qs, keep_blank_values=False, strict_parsing=False,
+				encoding='utf-8', errors='replace'):
+		parsed_result = {}
+		pairs = _parse_qsl(qs, keep_blank_values, strict_parsing,
+						encoding=encoding, errors=errors)
+		for name, value in pairs:
+			if name in parsed_result:
+				parsed_result[name].append(value)
+			else:
+				parsed_result[name] = [value]
+		return parsed_result
 
 try:
 	compat_str = unicode # Python 2