fix gh-2121

underlying memory of a boolean array may not be 0 and 1 when a boolean view is made from a non-boolean array, leading to unexpected results when copying element-wise, especially in astype

use a special path for boolean inputs to astype to make sure output is 0 and 1

Author: ndgrigorian

dpctl/tensor/_copy_utils.py

@@ -739,6 +739,9 @@ def astype(
             order=copy_order,
             buffer_ctor_kwargs={"queue": usm_ary.sycl_queue},
         )
+    # see #2121
+    if ary_dtype == dpt.bool:
+        usm_ary = dpt.not_equal(usm_ary, 0, order=order)
     _copy_from_usm_ndarray_to_usm_ndarray(R, usm_ary)
     return R