Ensure Xdr test isn't set up for a race condition
Ensure Xdr test isn't set up for a race condition

Hopefully we won't be mutating TestCommWorld any more in the future, but
if we do then this test is likely to see it, and we'd rather see that
via a deterministic parallel test failure instead of a race condition.

BalticPinguin/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,libMesh/libmesh,jwpeterson/libmesh,roystgnr/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,roystgnr/libmesh,libMesh/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,dschwen/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,dschwen/libmesh,roystgnr/libmesh,dschwen/libmesh,libMesh/libmesh,libMesh/libmesh,libMesh/libmesh,roystgnr/libmesh,roystgnr/libmesh,roystgnr/libmesh,libMesh/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,libMesh/libmesh,BalticPinguin/libmesh,libMesh/libmesh,dschwen/libmesh,dschwen/libmesh,dschwen/libmesh,jwpeterson/libmesh