BF: stride_tricks produces unwriteable array

Set unwriteable flag to prevent broadcast error

Author: effigies

nibabel/parrec.py

@@ -610,6 +610,7 @@ def __getitem__(self, slicer):
         # Broadcast scaling to shape of original data
         slopes, inters = self._slice_scaling
         fake_data = strided_scalar(self._shape)
+        fake_data.flags.writeable = False
         _, slopes, inters = np.broadcast_arrays(fake_data, slopes, inters)
         # Slice scaling to give output shape
         return raw_data * slopes[slicer] + inters[slicer]