[BUG] cudaErrorIllegalAddress while copying values to nullable string series

[cwharris]

Describe the bug
cudaErrorIllegalAddress while copying values to nullable string series. This is a regression from the behavior in 24.02.

Steps/Code to reproduce bug

cudf.Series(['a', None])[1:2] = ['b'] # cudaErrorIllegalAddress

However, the following does work:

cudf.Series(['a', 'b'])[1:2] = ['c'] # works

as does:

cudf.Series([0, 1])[1:2] = [2] # works

Expected behavior
expected the value to be copied to the specified range without causing cudaErrorIllegalAddress

Environment overview (please complete the following information)

• Environment location: Docker
• Method of cuDF install: conda

Additional context
Morpheus depends heavily on this behavior.

[davidwendt]

Also this works

cudf.Series(['a', None])[1:2] = 'b'

Broken down just to make sure:

>>> import cudf
>>> s = cudf.Series(['a', None])
>>> s[1:2] = 'b'
>>> s
0    a
1    b
dtype: object