As localTop may hold the updated value of top after the
compare_exchange failed.

"""
Otherwise, loads the actual value stored in *this into
expected (performs load operation).
"""

Co-authored-by: Nicolas Pfeiffer <nicolas.pfeiffer@fau.de>

because the hook is also invoked on resumption of the, now unblocked,
context.

Fixes a memory leak where the "from"-context would not be freed.

If we use getcurrentFiberPtr() then we will possibly run in a assert
witin that function.

It's 'ns' stupid.