FIX: removed encode on a bytes object

to_xml already returns a bytes object in python3, which can not be encoded.

Author: MichielCottaar

nibabel/cifti2/cifti2.py

@@ -770,7 +770,7 @@ def to_file_map(self, file_map=None):
         """
         from .parse_cifti2_fast import Cifti2Extension
         header = self.extra
-        extension = Cifti2Extension(content=self.header.to_xml().encode())
+        extension = Cifti2Extension(content=self.header.to_xml())
         header.extensions.append(extension)
         data = np.reshape(self.data, [1, 1, 1, 1] + list(self.data.shape))
         img = Nifti2Image(data, None, header)