OverflowError when computing slice indices practically means we'll
cannot allocate so much address space at next step:

    In [1]: s = slice(None)

    In [2]: s.indices(1<<62)
    Out[2]: (0, 4611686018427387904, 1)

    In [3]: s.indices(1<<63)
    ---------------------------------------------------------------------------
    OverflowError                             Traceback (most recent call last)
    <ipython-input-4-5aa549641bc6> in <module>()
    ----> 1 s.indices(1<<63)

    OverflowError: cannot fit 'long' into an index-sized integer

So translate this OverflowError into MemoryError (preserving message
details), because we'll need such "no so much address space" cases to
show up as MemoryError in a sooner patch.