Weird behavior of make on 10-STABLE, anyone else seeing this?

I've been working on porting OpenJFX, and ran into a weird problem with a Makefile that had me stumped. I finally stumbled upon a solution, but what I see looks like a pretty nasty bug in the system make command on 10-STABLE.

Here a minimal Makefile:
        echo $(PWD)

Put this in any directory and run make. You should be shown, as you would expect, the current directory. Now, create a sub-directory named objright where you are and try make again. Do you get something you don't expect?

This is on 10-STABLE, as I said. I don't see this on a 9.3 release system.

UPDATE: False alarm - make is supposed to do this. Must read the fine print about .OBJDIR in the man page. Now I wonder why I don't see it changing to the obj directory on my 9.3 system?