eclipse/jkube

I'm trying to migrate from Fabric8 Maven Plugin to OpenShift Maven Plugin, what we had working with FMP was a Docker based build with a Dockerfile and an inline assembly to add more files outside of the context. This is our configuration using FMP: https://github.com/syndesisio/syndesis/blob/c5362115c7adb09190059ed7dbb76a347e767d60/app/ui-react/pom.xml#L326-L360.
With JKube an attempt to use docker buildStrategy with a Dockerfile and an inline assembly leads to exception:

Failed to execute the build: Unable to build the image using the OpenShift build service: This image has already been flattened, you can only flatten the image once

It seems that AssemblyConfiguration::getFlattenedClone is called twice in this case: once from OpenshiftBuildService::build and subsequently from AssemblyManager::getAssemblyConfigurationForDockerfileMode.
At this point I'd like to explore if there is a way to achieve a docker based OpenShift build with Dockerfile and additional files outside of the context with OpenShift Maven Plugin.
I've found that including the empty <assembly> in this constelation triggers the issue, for example this will fail:

<plugin>
  <groupId>org.eclipse.jkube</groupId>
  <artifactId>openshift-maven-plugin</artifactId>
  <executions>
    <execution>
      <id>default-cli</id>
      <phase>package</phase>
      <goals>
        <goal>build</goal>
      </goals>
      <configuration>
        <skipBuildPom>false</skipBuildPom>
        <buildStrategy>docker</buildStrategy>
        <images>
          <image>
            <name>test</name>
            <build>
              <dockerFile>${basedir}/docker/Dockerfile</dockerFile>
              <assembly />
            </build>
          </image>
        </images>
      </configuration>
    </execution>
  </executions>
</plugin>