http: Do not use chained add_extension syntax on a single statement.

For consistency with other places in caucase.

caucase/ca.py

@@ -37,7 +37,7 @@ from .exceptions import (
   NotACertificateSigningRequest,
 )
 
-__all__ = ('CertificateAuthority', 'UserCertificateAuthority')
+__all__ = ('CertificateAuthority', 'UserCertificateAuthority', 'Extension')
 
 _cryptography_backend = default_backend()
 _AUTO_SIGNED_NO = 0

caucase/http.py

@@ -41,7 +41,7 @@ import pem
 from . import exceptions
 from . import utils
 from .wsgi import Application
-from .ca import CertificateAuthority, UserCertificateAuthority
+from .ca import CertificateAuthority, UserCertificateAuthority, Extension
 from .storage import SQLite3Storage
 from .http_wsgirequesthandler import WSGIRequestHandler
 
@@ -226,14 +226,14 @@ def getSSLContext(
     csr_id = cas.appendCertificateSigningRequest(
       csr_pem=utils.dump_certificate_request(
         x509.CertificateSigningRequestBuilder(
-        ).subject_name(
-          x509.Name([
+          subject_name=x509.Name([
             x509.NameAttribute(
               oid=x509.oid.NameOID.COMMON_NAME,
               value=hostname.decode('ascii'),
             ),
           ]),
-        ).add_extension(
+          extensions=[
+            Extension(
               x509.KeyUsage(
                 # pylint: disable=bad-whitespace
                 digital_signature =True,
@@ -248,11 +248,14 @@ def getSSLContext(
                 # pylint: enable=bad-whitespace
               ),
               critical=True,
-        ).add_extension(
+            ),
+            Extension(
               x509.SubjectAlternativeName([
                 x509.DNSName(hostname.decode('ascii')),
               ]),
               critical=True,
+            ),
+          ],
         ).sign(
           private_key=new_key,
           algorithm=utils.DEFAULT_DIGEST_CLASS(),