All - Only 6 months after I promised the code would be done, the changes we discussed in February around 3rd party packages (Libevent, HWLOC, PMIx, and PRRTE) are merged to master. With these changes, Open MPI will prefer an external version of any of those packages if a "new enough" version is found already installed on the system. New enough is no longer defined as "newer than the built-in package", but is defined as "as new as the oldest version we know works". This may cause unexpected changes from using the built-in versions to the system versions for some packages, particularly libevent.
If you have Libevent and hwloc pre-installed, your total build times will go down a couple percent, so there's that :). Brian