PackWar must not fail on inexisting repositories

$ ./bin/nuxeoctl pack /tmp/nuxeo.war
(...)
Detected Tomcat server.
Running custom installation for container: nxserver
Scanning directory: bundles
Scanning directory: plugins
Preprocessing order: 
	org.nuxeo.ecm.core.management (nuxeo-core-management-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.oauth (nuxeo-platform-oauth-8.4-SNAPSHOT.jar)
	org.nuxeo.theme.styling (nuxeo-theme-styling-8.4-SNAPSHOT.jar)
	org.nuxeo.runtime.nuxeo-runtime-deploy (nuxeo-runtime-deploy-8.4-SNAPSHOT.jar)
	org.nuxeo.web.resources.rest (nuxeo-web-resources-rest-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.webengine.core (nuxeo-webengine-core-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.ws.sun.jaxws (nuxeo-platform-ws-sun-jaxws-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.webdav (nuxeo-webdav-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.lang (nuxeo-platform-lang-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.login.token (nuxeo-platform-login-token-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.collections.core (nuxeo-platform-collections-core-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.rendition.publisher (nuxeo-platform-rendition-publisher-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.lang.ext (nuxeo-platform-lang-ext-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.user.center.profile (nuxeo-user-profile-8.4-SNAPSHOT.jar)
	org.nuxeo.elasticsearch.core (nuxeo-elasticsearch-core-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.restapi.server (nuxeo-rest-api-server-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.core.management.jtajca (nuxeo-core-management-jtajca-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.web.common (nuxeo-platform-web-common-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.core.opencmis.bindings (nuxeo-opencmis-bindings-8.4-SNAPSHOT.jar)
	org.nuxeo.ecm.platform.routing.default (nuxeo-routing-default-8.4-SNAPSHOT.jar)
Running custom installation for fragment: org.nuxeo.ecm.platform.oauth
Running custom installation for fragment: org.nuxeo.ecm.platform.lang
Running custom installation for fragment: org.nuxeo.ecm.platform.login.token
Running custom installation for fragment: org.nuxeo.ecm.platform.collections.core
Running custom installation for fragment: org.nuxeo.ecm.platform.rendition.publisher
Running custom installation for fragment: org.nuxeo.ecm.platform.lang.ext
Running custom installation for fragment: org.nuxeo.ecm.user.center.profile
Running custom installation for fragment: org.nuxeo.ecm.core.opencmis.bindings
Running custom installation for fragment: org.nuxeo.ecm.platform.routing.default
Exception in thread "main" java.lang.NullPointerException
	at org.nuxeo.runtime.deployment.preprocessor.PackWar.zipTree(PackWar.java:296)
	at org.nuxeo.runtime.deployment.preprocessor.PackWar.executePackaging(PackWar.java:220)
	at org.nuxeo.runtime.deployment.preprocessor.PackWar.execute(PackWar.java:167)
	at org.nuxeo.runtime.deployment.preprocessor.PackWar.main(PackWar.java:531)