python: Only use features found in Debian Stable (Debian 9)

  - CDefError is not exposed as cffi.error.CDefError, but as
    cffi.api.CDefError in python3-cffi 1.9.1-2.  This change is
    forwards compatible with python3-cffi 1.11.5-3 (from Debian
    Testing).

  - enum.auto is only available in Python v3.6.  Albeit uglier,
    manually assigning values works in Python v3.5 (and later).

2 files changed, 11 insertions, 7 deletions

diff --git a/ffi/lang/python/sequoia/sequoia_build.py b/ffi/lang/python/sequoia/sequoia_build.py
index ea0ad9df..7345097b 100644
--- a/ffi/lang/python/sequoia/sequoia_build.py
+++ b/ffi/lang/python/sequoia/sequoia_build.py
@@ -1,5 +1,6 @@
 from os.path import join, dirname
-from cffi import FFI, error
+from cffi import FFI
+from cffi.api import CDefError
 from itertools import chain
 
 sq_inc = join(dirname(__file__), '../../../include/sequoia')
@@ -29,7 +30,7 @@ ffibuilder.cdef('void free (void *ptr);')
 
 try:
     ffibuilder.cdef(defs, override=True)
-except error.CDefError as e:
+except CDefError as e:
     try:
         current_decl = e.args[1]
         linenum = current_decl.coord.line
diff --git a/ffi/lang/python/tests/test_packet_parser.py b/ffi/lang/python/tests/test_packet_parser.py
index 1c134f6f..de126bc3 100644
--- a/ffi/lang/python/tests/test_packet_parser.py
+++ b/ffi/lang/python/tests/test_packet_parser.py
@@ -1,4 +1,4 @@
-from enum import Enum, auto
+from enum import Enum
 from sequoia.core import Context, NetworkPolicy
 from sequoia.openpgp import Tag, PacketParser
 
@@ -11,10 +11,13 @@ def test_decryption():
                   ephemeral=True)
 
     class State(Enum):
-        Start = auto()
-        Decrypted = auto()
-        Deciphered = auto()
-        Done = auto()
+        # XXX: In Python 3.6, we can use enum.auto() to assign values.
+        # But we want to support Debian 9, which uses Python 3.5, as
+        # long as it is Debian stable.
+        Start = 1
+        Decrypted = 2
+        Deciphered = 3
+        Done = 4
 
     state = State.Start
     algo, key = None, None