FIX: Only find paths for created files

Author: effigies

nipype/interfaces/base/core.py

@@ -1149,8 +1149,9 @@ def _list_outputs(self):
                 out_name = name
                 if trait_spec.output_name is not None:
                     out_name = trait_spec.output_name
-                outputs[out_name] = \
-                    os.path.abspath(self._filename_from_source(name))
+                fname = self._filename_from_source(name)
+                if isdefined(fname):
+                    outputs[out_name] = os.path.abspath(fname)
             return outputs
 
     def _parse_inputs(self, skip=None):

nipype/interfaces/fsl/tests/test_preprocess.py

@@ -313,6 +313,7 @@ def test_flirt(setup_flirt):
         os.path.join(os.getcwd(), flirter.inputs.out_file)
     assert outs['out_matrix_file'] == \
         os.path.join(os.getcwd(), flirter.inputs.out_matrix_file)
+    assert not isdefined(flirter.inputs.out_log)
 
 
 # Mcflirt