We noticed that old branches of Scylla had problems with looking up a
null value in a local secondary index - hanging or crashing. This patch
includes tests to reproduce these bugs. The tests pass on current
master - apparently this bug has already been fixed, but we didn't
have a regression test for it.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Closes#12570