Need DDT fixes ported to v3.0.x and v3.1.x

[jsquyres]

@bosilca @ggouaillardet: Could I impose on you to port the commits from #6295 and #6326 to v3.0.x and v3.1.x?

I ask because we apparently need these to fix #6285 for v3.0.x and v3.1.x.

I tried cherry-picking them, but I run into conflicts, and I'm a bit nervous about trying to sort through this code to get the right resolutions.

FYI: @edgargabriel @ax3l

[bosilca]

They are both pending.

[jsquyres]

These are now both merged to v3.0.x and v3.1.x. Closing.