python2.pkgs.cryptography: fixup build of dependants

... most notably fix pyopenssl. I can't say I really understand this,
but the commit seems safe enough.

+2 -1
+2 -1
pkgs/development/python-modules/cryptography/default.nix
··· 17 17 , iso8601 18 18 , pytz 19 19 , hypothesis 20 + , enum34 20 21 }: 21 22 22 23 buildPythonPackage rec { ··· 36 37 packaging 37 38 six 38 39 ] ++ stdenv.lib.optional (!isPyPy) cffi 39 - ++ stdenv.lib.optionals isPy27 [ ipaddress ]; 40 + ++ stdenv.lib.optionals isPy27 [ ipaddress enum34 ]; 40 41 41 42 checkInputs = [ 42 43 cryptography_vectors