make install-oss rebuilds the entire project

[williewillus]

Expectation

make oss produces the binaries, make install-oss puts them in the specified DESTDIR

Actual

make install-oss completely rebuilds the project even though make oss just built them

Repro: I've packaged this project in the Arch AUR here https://aur.archlinux.org/packages/sapling-scm The PKGBUILD performs a build by make PREFIX=/usr oss, then an install by make PREFIX=/usr DESTDIR="$pkgdir/" install-oss. In the install stage, the project is fully rebuilt instead of just being copied to the destination.

[shish]

Looks like make oss followed by make oss rebuilds the entire project too, so it looks like this isn't a case of "make oss and make install-oss use different caches", but "make is invalidating the caches every time it runs"?