Profile 2 in 2.9 depends on older APIs and thus cannot be built in offline mode with the rest of Sakai
Version 1.2.0 of common-edu-person for example.
[ERROR] Failed to execute goal on project profile2-api: Could not resolve dependencies for project org.sakaiproject.profile2:profile2-api:jar:1.5.2: The following artifacts could not be resolved: org.sakaiproject.common:sakai-common-edu-person-api:jar:1.2.0, org.sakaiproject.entitybroker:entitybroker-api:jar:1.5.0, org.sakaiproject.kernel:sakai-kernel-api:jar:1.3.0: The repository system is offline but the artifact org.sakaiproject.common:sakai-common-edu-person-api:jar:1.2.0 is not available in the local repository. -> [Help 1]
It would be better if instead, it would rely on the versions included with 2.9.x or the current 2.9 release when the code is checked out as part of that overall build. This is probably not going to be possible for the tags but for the .x branch and trunk it should really depend on the same versions included in the 2.9.x codebase like the rest of the core code.