Intermittent failure of `test1000`

[mdavidsaver]

Something I've noticed in recent months. I'm not sure exactly when this started. With some occurances there is an associated evbase self-joining error. I have yet to get a stack trace to see where the extra reference is being held.

   test1000.tap ..... 
  not ok 1001 - Instance leak ServerGPRConnect : 102
  not ok 1002 - Instance leak SharedPVImpl : 997
  not ok 1003 - Instance leak StructTop : 1103
  not ok 1004 - Instance leak UDPListener : 2
  not ok 1005 - Instance leak evbase : 2
  not ok 1006 - Instance leak evbaseRunning : 2

I suspect there is an actual regression behind this.