Pegasus fails to plan a workflow that has a container of type singularity and the image url points to docker hub.

Example TC:
cont hic_hq_image {
type "singularity"
image "docker:///papajim/hic_hq:latest"
}

Error Message:
2018.09.13 15:55:24.219 PDT: [FATAL ERROR]
 [1]: Unable to instantiate Transformation Catalog at edu.isi.pegasus.planner.catalog.transformation.TransformationFactory.loadInstance(TransformationFactory.java:172)
 [2]: edu.isi.pegasus.planner.catalog.transformation.impl.Text caught edu.isi.pegasus.planner.parser.ScannerException line 8: at edu.isi.pegasus.planner.parser.TransformationCatalogTextParser.parse(TransformationCatalogTextParser.java:236)
 [3]: Unable to compute singularity extension from url url -> docker:///papajim/hic_hq:latest , protocol -> docker , host -> , path -> /papajim/hic_hq:latest , url-prefix -> docker:// at edu.isi.pegasus.planner.catalog.transformation.classes.Container.computeLFN(Container.java:184)
ERROR while logging metrics The metrics file location is not yet initialized


Planning the workflow is successful when I I change the container specification in the transformation catalog to type "docker" :
cont hic_hq_image {
type "docker"
image "docker:///papajim/hic_hq:latest"
}

I have attached a verbose output from the planner. I've tested this with 4.8.4, but the output is from 4.8.2. Still the same error though.