The build rules for the Octave packages (default-octave.mk, stable-octave.mk, release-octave.mk) install Octave to two different locations: One with all the other packages (the --prefix location) and another one in a directory that seems to be reserved for Octave:
$(MAKE) -C '$(1)/.build' -j '$(JOBS)' DESTDIR=$(TOP_BUILD_DIR)/octave install; \
Why do we need that second, separate installation location?
For a test, I removed that installation step: Creating the Windows
nsis-installer seems to work fine without that second installation.
Is it ok to remove that step?