More specific error handling

Author: oesteban

nipype/algorithms/mesh.py

@@ -67,16 +67,23 @@ def _triangle_area(self, A, B, C):
         return area
 
     def _run_interface(self, runtime):
-        try:
-            from enthought.etsconfig.api import ETSConfig
-            ETSConfig.toolkit = 'null'
-        except:
-            raise RuntimeError('P2PDistance could not access ETSConfig')
         try:
             from tvtk.api import tvtk
         except ImportError:
             raise ImportError('Interface P2PDistance requires tvtk')
 
+        try:
+            from enthought.etsconfig.api import ETSConfig
+        except ImportError:
+            iflogger.warn(('ETS toolkit could not be imported'))
+        else:
+            try:
+                ETSConfig.toolkit = 'null'
+            except:
+                iflogger.warn(('ETS toolkit could not be set to \'null\' '
+                               'for headless operation'))
+                pass
+
         r1 = tvtk.PolyDataReader(file_name=self.inputs.surface1)
         r2 = tvtk.PolyDataReader(file_name=self.inputs.surface2)
         vtk1 = r1.output