Fixes the following security vulnerability:
CVE-2019-9740: An issue was discovered in urllib2 in Python 2.x through
2.7.16 and urllib in Python 3.x through 3.7.3. CRLF injection is possible
if the attacker controls a url parameter, as demonstrated by the first
argument to urllib.request.urlopen with \r\n (specifically in the query
string after a ? character) followed by an HTTP header or a Redis command.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>