Commit 7e98c295c1bb511ece51b5f8c97f26c173ddaf76, which is cherry-picked rocko adds a change which removes a duplicate defconfig directive from the list of config fragments (sccs). If a configuration file is named "my-device-defconfig" it will be left as "my-device-", which breaks the build. 

Offending line:
+           sccs_from_src_uri=$(echo $sccs_from_src_uri | sed 's/defconfig//g')

Is this intentional and one should update the layer to not use "defconfig" in the configuration fragments names?