fixed treatment of filename when namesource is not a file

Author: dmordom

nipype/interfaces/base.py

@@ -1475,7 +1475,11 @@ def _filename_from_source(self, name):
             source = getattr(self.inputs, name_source)
             while isinstance(source, list):
                 source = source[0]
-            _, base, _ = split_filename(source)
+            #special treatment for files
+            if isinstance(source, str) and os.path.exists(source):
+                _, base, _ = split_filename(source)
+            else:
+                base = source
             retval = name_template % base
             _, _, ext = split_filename(retval)
             if trait_spec.keep_extension and ext: