sslutil: work around SSLContext.get_ca_certs bug on Windows (issue5313) SSLContext.get_ca_certs() can raise "ssl.SSLError: unknown error (_ssl.c:636)" on Windows. See https://bugs.python.org/issue20916 for more info. We add a try..except that swallows the exception to work around this bug. If we encounter the bug, we won't print a warning message about attempting to load CA certificates. This is unfortunate. But there appears to be little we can do :/