org.semanticweb.owlapi.model.ImmutableOWLOntologyChangeException: Cannot apply changes to immutable ontology: null

[NicolasRouquette]

I'm trying to use ecco to diff changes in these ontologies: https://github.com/JPL-IMCE/gov.nasa.jpl.imce.ontologies.public/tree/master/ontologies

./ecco.sh -ont1 `pwd`/C/imce.jpl.nasa.gov/foundation/base/base.owl -ont2 `pwd`/W/imce.jpl.nasa.gov/foundation/base/base.owl -r -c at -v
starting ecco...

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	     ecco: a diff tool for OWL 2 ontologies
	        v2.7 released on 16-Feb-2015
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by Rafael Goncalves. Powered by the OWL API version 3.5.1


Input 1: base.owl (/opt/local/imce/users/nfr/current/C/imce.jpl.nasa.gov/foundation/base/base.owl)
Input 2: base.owl (/opt/local/imce/users/nfr/current/W/imce.jpl.nasa.gov/foundation/base/base.owl)
Exception in thread "main" org.semanticweb.owlapi.model.ImmutableOWLOntologyChangeException: Cannot apply changes to immutable ontology: null
	at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.enactChangeApplication(OWLOntologyManagerImpl.java:479)
	at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.applyChanges(OWLOntologyManagerImpl.java:502)
	at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.applyChange(OWLOntologyManagerImpl.java:544)
	at uk.ac.manchester.cs.diff.Ecco.removeImports(Ecco.java:454)
	at uk.ac.manchester.cs.diff.Ecco.verifyInput(Ecco.java:375)
	at uk.ac.manchester.cs.diff.Ecco.computeDiff(Ecco.java:87)
	at uk.ac.manchester.cs.diff.EccoRunner.start(EccoRunner.java:88)
	at uk.ac.manchester.cs.diff.EccoRunner.main(EccoRunner.java:223)