In a couple of places in sstable_datafile_test.cc, we had
make_shared<memtable> instead of the usual make_lw_shared<memtable>.
It appears that since commit bc468f9a0e,
which made memtables inherit from enable_lw_shared_from_this (not the "lw"),
this no longer works correctly. I'm not sure I can really explain the
details of what's wrong, but with some refactoring I did on the sstable
writing code, it stopped working giving various strange crashes which appear
like the object protected by this shared_ptr got prematurely destructed.
Changing the test to use make_lw_shared() fixes the problems I was having.
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>