NullPointerException in gradle lintVitalRelease when testing new app in fdroiddata

I tried to add my own app to fdroiddata locally and followed the contributing guidelines.

When building my app I got an error from gradle:

$ fdroid build -v -l de.cweiske.headphoneindicator
...
:compileReleaseSources
:lintVitalRelease FAILED
...
* What went wrong:
Execution failed for task ':lintVitalRelease'.
> java.lang.NullPointerException (no error message)

The stack trace http://p.cweiske.de/310#full.txt pointed to

Caused by: java.lang.NullPointerException
    at com.android.build.gradle.internal.NdkHandler.resolveCompileSdkVersion(NdkHandler.java:116)

which I could get away when removing the auto-generated lines

ndk.dir=$ANDROID_NDK
ndk-location=$ANDROID_NDK

in the package's local.properties file.

I then tried to convince fdroid to not generate this lines in local.properties by setting

ndk_paths = None

or

ndk_paths = {
    'r9b': None,
    'r10e': None,
}

but that does not work.

My app does not need the NDK, and my harddisk doesn't want another 1GiB of files.

Is there anything I can do to make my test build work without an NDK?