(maint) Harness adjusts packaging paths based on rc status

Packaging repository sets package paths to devel or products based on rc
status of the commit being packaged.  So we adjust our pathing based on
git describe info recorded in the build artifact being tarred from the
base Rakefile ci:el6tests task.  The git info is injectable because we
may be packaging a different commit then the one containing the tests we
are pushing into the build artifact.