BF - python 3 compatibility fixes

Author: matthew-brett

nibabel/arraywriters.py

@@ -56,7 +56,7 @@ def __init__(self, array, out_dtype=None, calc_scale=True):
         --------
         >>> arr = np.array([0, 255], np.uint8)
         >>> aw = ArrayWriter(arr)
-        >>> aw = ArrayWriter(arr, np.int8)
+        >>> aw = ArrayWriter(arr, np.int8) #doctest: +IGNORE_EXCEPTION_DETAIL
         Traceback (most recent call last):
             ...
         WriterError: Scaling needed but cannot scale

nibabel/volumeutils.py

@@ -685,7 +685,7 @@ def write_zeros(fileobj, count, block_size=8194):
     block_size : int, optional
         largest continuous block to write.
     """
-    nblocks = count / block_size
+    nblocks = int(count // block_size)
     rem = count % block_size
     blk = ZEROB * block_size
     for bno in range(nblocks):