magnum-plugins: don't enable Basis on 2019.10.

It doesn't know about the bundled location there yet. Yes I'm needlessly
downloading all the sources and then ignoring them, but whatever, a new
version will be out soon anyway.

Formula/magnum-plugins.rb

@@ -35,9 +35,15 @@ def install
       system "tar", "xzvf", "meshoptimizer.tar.gz", "-C", "meshoptimizer", "--strip-components=1"
     end
 
+    # Temporarily disable Basis on 2019.10 because there it doesn't understand
+    # the bundled location yet and would fail. MeshOptimizer wasn't there yet
+    # so that's okay; we don't care that the sources are downloaded above but
+    # unused. TODO: remove when next stable is out
+    basis = head? ? "ON" : "OFF"
+
     system "mkdir build"
     cd "build" do
-      system "cmake", "-DCMAKE_BUILD_TYPE=Release", "-DCMAKE_INSTALL_PREFIX=#{prefix}", "-DWITH_ASSIMPIMPORTER=ON", "-DWITH_BASISIMAGECONVERTER=ON", "-DWITH_BASISIMPORTER=ON", "-DWITH_DDSIMPORTER=ON", "-DWITH_DEVILIMAGEIMPORTER=ON", "-DWITH_DRFLACAUDIOIMPORTER=ON", "-DWITH_DRMP3AUDIOIMPORTER=ON", "-DWITH_DRWAVAUDIOIMPORTER=ON", "-DWITH_FAAD2AUDIOIMPORTER=ON", "-DWITH_FREETYPEFONT=ON", "-DWITH_HARFBUZZFONT=ON", "-DWITH_JPEGIMAGECONVERTER=ON", "-DWITH_JPEGIMPORTER=ON", "-DWITH_MESHOPTIMIZERSCENECONVERTER=ON", "-DWITH_MINIEXRIMAGECONVERTER=ON", "-DWITH_OPENGEXIMPORTER=ON", "-DWITH_PNGIMAGECONVERTER=ON", "-DWITH_PNGIMPORTER=ON", "-DWITH_PRIMITIVEIMPORTER=ON", "-DWITH_STANFORDIMPORTER=ON", "-DWITH_STANFORDSCENECONVERTER=ON", "-DWITH_STBIMAGECONVERTER=ON", "-DWITH_STBIMAGEIMPORTER=ON", "-DWITH_STBTRUETYPEFONT=ON", "-DWITH_STBVORBISAUDIOIMPORTER=ON", "-DWITH_STLIMPORTER=ON", "-DWITH_TINYGLTFIMPORTER=ON", ".."
+      system "cmake", "-DCMAKE_BUILD_TYPE=Release", "-DCMAKE_INSTALL_PREFIX=#{prefix}", "-DWITH_ASSIMPIMPORTER=ON", "-DWITH_BASISIMAGECONVERTER=#{basis}", "-DWITH_BASISIMPORTER=#{basis}", "-DWITH_DDSIMPORTER=ON", "-DWITH_DEVILIMAGEIMPORTER=ON", "-DWITH_DRFLACAUDIOIMPORTER=ON", "-DWITH_DRMP3AUDIOIMPORTER=ON", "-DWITH_DRWAVAUDIOIMPORTER=ON", "-DWITH_FAAD2AUDIOIMPORTER=ON", "-DWITH_FREETYPEFONT=ON", "-DWITH_HARFBUZZFONT=ON", "-DWITH_JPEGIMAGECONVERTER=ON", "-DWITH_JPEGIMPORTER=ON", "-DWITH_MESHOPTIMIZERSCENECONVERTER=ON", "-DWITH_MINIEXRIMAGECONVERTER=ON", "-DWITH_OPENGEXIMPORTER=ON", "-DWITH_PNGIMAGECONVERTER=ON", "-DWITH_PNGIMPORTER=ON", "-DWITH_PRIMITIVEIMPORTER=ON", "-DWITH_STANFORDIMPORTER=ON", "-DWITH_STANFORDSCENECONVERTER=ON", "-DWITH_STBIMAGECONVERTER=ON", "-DWITH_STBIMAGEIMPORTER=ON", "-DWITH_STBTRUETYPEFONT=ON", "-DWITH_STBVORBISAUDIOIMPORTER=ON", "-DWITH_STLIMPORTER=ON", "-DWITH_TINYGLTFIMPORTER=ON", ".."
       system "cmake", "--build", "."
       system "cmake", "--build", ".", "--target", "install"
     end