pyspark app with "spark.jars.packages" config does not work

Command "pyspark --packages" works as expected, but if submitting a livy pyspark job with "spark.jars.packages" config, the downloaded packages are not added to python's sys.path therefore the package is not available to use.

For example, this command works:

pyspark --packages Azure:mmlspark:0.14

However, using Jupyter notebook with sparkmagic kernel to open a pyspark session failed:

%%configure -f {"conf": {spark.jars.packages": "Azure:mmlspark:0.14"}}
import mmlspark

The root cause is that SparkSubmit determines pyspark app by the suffix of primary resource but Livy uses "spark-internal" as the primary resource when calling spark-submit, therefore args.isPython is set to false in SparkSubmit.scala.