Bug PB5: Subdividing edges changes face material

I've been seeing this since upgrading to PB 5. Here's an edge I'm going to subdivide in order to add vertices at the two corners of the tile wall:



I select the edge, and press "Subdivide Edges", and this is the result:



Simply subdividing the edge changes the material on the adjacent face. It's worth pointing out that the material that got assign is material [0] in the material list for the renderer. I don't know if that's a coincidence, or whether something is falling back on assigning material 0 to things.

Here's another example. Prior to subdividing that edge:



And after subdividing:

 

This is still an issue in the new 5.0.0-pre.10 version. (Though nice work on this new release, as I think it fixed all the other bugs I had noticed in earlier 5.0 previews. )

 

Submitted as #1311258, with repro project.

Quick repro: Create a PB cube, put at least two materials on it, then subdivide any edge between faces of different materials. One of the faces will have its material reset to materials[0].