Reduce memory usage of manyclients.js
Revert "SERVER-13627 Test that replSetReconfig prohibits 0-vote arbiter."

This reverts commit 6eccc037b1e6d22d60d0e7aec39dcc183a756790.
SERVER-13951 Remove ROLLBACK_ENABLED flag

Rollback is now required so we don't need a way to turn it off.
SERVER-15165 Check invariant before early return
Merge remote-tracking branch 'upstream/master'