configure fails when only qtdeclarative and qtbase are checked out

I checked out a top-level qt5, ran init-repository --module-subset --branch qtbase,qtdeclarative, all checked out on dev, made myself a build directory and, in it, ran configure with the features and paths that Coin uses for its build, but making a no-optimize-debug developer build.
When configure was configuring qtdeclarative, it warned about not finding the shader-tools config, then failed because it couldn't find Qt6Quick's config, which it seemed to think it needed.

Checking out qtshadertools and re-running configure solved the problem, but qtdeclarative/dependencies.yaml claims required: false for shader-tools, so this surely should not have been necessary.

Note that I had in no sense requested Qt6Quick, beyond trying to configure with qtdeclarative checked out.

Command-line (here broken up with backslash-linebreaks for readability) was:

..\..\eddy\configure -platform win32-g++ -developer-build -no-optimize-debug -- \
	-DQT_BUILD_TESTS=ON -DQT_BUILD_TESTS_BY_DEFAULT=OFF -Wno-dev --log-level=NOTICE \
	-DFEATURE_separate_debug_info=ON -DQT_BUILD_EXAMPLES=OFF \
	-DOPENSSL_ROOT_DIR=C:\openssl -DFEATURE_system_zlib=OFF -DFEATURE_system_tiff=OFF \
	-DFEATURE_system_freetype=OFF -DFEATURE_system_jpeg=OFF \
	-DPostgreSQL_ROOT=C:\Utils\postgresql\pgsql