message: build: running a vendored build+tests on gentoo fails with 'RUSTUP=0 VENDORED=1 make {,tests}', so only use the toolchain if RUSTUP==1
diff: @@ -57,7 +57,7 @@ CPU_CORES=$(nproc --all)
  # Build debug binary
  # Check if the variabl $RUSTUP is set. If yes the $TOOLCHAIN can be choosen via cargo, otherwise cargo might not now
  # about that feature.
  -if [ -v RUSTUP ]; then
  +if [ -v RUSTUP ] && [ "${RUSTUP}" -eq 1 ]; then
  cargo +$TOOLCHAIN build
  else
  cargo build
  