I just ran into this issue today trying to port a relatively large build system to use `subdir-objects`.
This is quite annoying as everything else works just fine, but this bug either prevents me from using `subdir-objects` at all or forces me to rewrite these parts using a completely different approach. Also, I would believe it should be relatively easy to fix as distclean basically just *removes* files anyway. And the fact the problem here is that a file is already gone sounds a bit ironic :)