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.