I'm not certain it's not a problem on my end, but I tried wiping my build directory and starting over with just ../configure --prefix=~/local, on the incoming branch.

When I try to uninstall, I get rm: cannot remove ‘<prefix>/lib/’: Is a directory and I think it's because of the bits in mk/install.mk where it says $(Q)rm -f $(PHL)/$(CFG_FUZZER), (and .../CFG_CARGO and .../CFG_RUSTDOC), with the CFG_ bits evaluating to empty strings.

I don't understand the build system, but git blame on that file pointed me at 6c79d78, so I think I should mention @dbp.