python2: Don't fail silently on module build.

A build output of such a failure can be found here:

http://hydra.nixos.org/build/21994789/nixlog/1/raw

The build_ext command doesn't return non-zero if it fails but instead
produces a file with a "_failed.so" suffix, which we're now checking
after the build_ext command.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/development/interpreters/python/2.6/default.nix

@@ -144,6 +144,7 @@ let
             'self.extensions = [ext for ext in self.extensions if ext.name in ["${internalName}"]]'
 
           python ./setup.py build_ext
+          [ -z "$(find build -name '*_failed.so' -print)" ]
         '';
 
       installPhase =

pkgs/development/interpreters/python/2.7/default.nix

@@ -161,6 +161,7 @@ let
             'self.extensions = [ext for ext in self.extensions if ext.name in ["${internalName}"]]'
 
           python ./setup.py build_ext
+          [ -z "$(find build -name '*_failed.so' -print)" ]
         '';
 
       installPhase =