Add note to serial_number parameter about entropy

- Add reference to random-numbers.rst for easy intra-linking
- Document critical parameter of CertificateBuilder.add_extension
- Support InhibitAnyPolicy in the CertificateBuilder frontend but not
  in the backend
- Slim down more tests
- Fix up test that asserts the backend does not allow for unsupported
  extensions

1 files changed, 2 insertions, 0 deletions

diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index 5760aae7..9f6cda13 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -1720,6 +1720,8 @@ class CertificateBuilder(object):
             extension = Extension(
                 OID_SUBJECT_ALTERNATIVE_NAME, critical, extension
             )
+        elif isinstance(extension, InhibitAnyPolicy):
+            extension = Extension(OID_INHIBIT_ANY_POLICY, critical, extension)
         else:
             raise NotImplementedError('Unsupported X.509 extension.')