sty: clarity suggestions from @mgxd

See #2962 (review)

Author: oesteban

nipype/interfaces/io.py

@@ -1027,9 +1027,9 @@ def s3tolocal(self, s3path, bkt):
         local_directory = str(self.inputs.local_directory)
         bucket_path = str(self.inputs.bucket_path)
         template = str(self.inputs.template)
-        if not os.path.split(local_directory)[1] == '':
+        if not os.path.basename(local_directory) == '':
             local_directory += '/'
-        if not os.path.split(bucket_path)[1] == '':
+        if not os.path.basename(bucket_path) == '':
             bucket_path += '/'
         if template[0] == '/':
             template = template[1:]