jstests/drop2.js fails consistently on my local machine when built with the now-default v8. My machine is Ubuntu Linux, doing a 64 bit debug build. Weirdly, this test doesn't seem to be failing on buildbot, though it fails for me every time. If I compile mongod with --usesm, the test passes.
I have attached the output of running the test twice, once with mongod compiled using default flags, and once with mongod compiled using --usesm.