SERVER-22449 means that failures in these functions will now correctly cause exceptions to be raised.

However, it is useful for users and support to receive positive feedback when the operations succeed.

This is so that success can be known immediately after the function has run, without needing to determine whether or not the user is running a post-SERVER-22449 version of the shell (ie. whether or not there would have been an exception).

For most of the sh.* functions, this just means adding return in front of the assert.writeOK. startBalancer and stopBalancer will likely be a little less straightforward.