Change AOSP and build SDK

When applying OpenPDroid patches to Android 4.4.2_r1 AOSP by doing

cd ~/androidsource/

repo init -u https://android.googlesource.com/platform/manifest -b android-4.4.2_r1 -g all 
# "-g all" is important to be able to build the sdk

repo sync

cd ~/androidsource/build; git checkout -b openpdroid; patch -p1 < ~/openpdroid_4.4_build.patch
    cd ~/androidsource/libcore; git checkout -b openpdroid; patch -p1 < ~/openpdroid_4.4_libcore.patch
    cd ~/androidsource/packages/apps/Mms; git checkout -b openpdroid; patch -p1 < ~/openpdroid_4.4_packages_apps_Mms.patch
    cd ~/androidsource/frameworks/base; git checkout -b openpdroid; patch -p1 < ~/openpdroid_4.4_frameworks_base.patch
    cd ~/androidsource/frameworks/opt/telephony; git checkout -b openpdroid; patch -p1 < ~/openpdroid_4.4_frameworks_opt_telephony.patch

I can build without problems

. build/envsetup.sh
lunch aosp_arm-eng
make update-api
make

and then I can run the OpenPDroid application that uses the user API.

However i cant build

. build/envsetup.sh
lunch sdk-eng
make update-api
make sdk

This causes the following error:

build/core/main.mk:662: *** : Module 'PDroid' in PRODUCT_PACKAGES has nothing to install!.  Stop.

When searching for a problem, people assume that you just need to remove the corresponding module, in my case "PDroid". But will this not eliminate the whole purpose of the patch if I remove PDroid from PRODUCT_PACKAGES?

I tried to comment on the checks made at build/core/main.mk. Then I can create the SDK, but then the added packages are not part of the custom SDK (which assumes that nothing has been created for the PDODI module).

What is missing to create a new SDK?