mojo required full path for $MOJO_SPEC

stg-ue-error-tracker@wendigo:~$ mojo run --project mojo-stg-ue-error-tracker --series trusty --stage ue/mojo-ue-error-tracker/staging mojo-error-tracker
2016-02-16 18:24:43 [INFO] Using pre-existing container class lxc
2016-02-16 18:24:43 [INFO] Rsyncing mojo-error-tracker to spec
2016-02-16 18:24:43 [ERROR] Unknown error
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/mojo/cli.py", line 503, in run_with_args
    args.func(args)
  File "/usr/lib/python2.7/dist-packages/mojo/utils.py", line 305, in wrapped
    return method(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/mojo/cli.py", line 287, in run_from_manifest
    logfile=args.logfile)
  File "/usr/lib/python2.7/dist-packages/mojo/project.py", line 296, in create_workspace
    ws.prepare()
  File "/usr/lib/python2.7/dist-packages/mojo/workspace.py", line 58, in prepare
    self.spec # Initializes spec
  File "/usr/lib/python2.7/dist-packages/mojo/workspace.py", line 35, in spec
    self._spec = Spec(self.spec_dir, self.spec_url, stage=self.stage, manifest_file=self.manifest_file)
  File "/usr/lib/python2.7/dist-packages/mojo/spec.py", line 33, in __init__
    self.ct.run() # Process the codetree directive, ie branch, pull, etc
  File "/usr/lib/python2.7/dist-packages/codetree/config.py", line 44, in run
    return self.source.get(self.location, self.source_options)
  File "/usr/lib/python2.7/dist-packages/codetree/handlers/basic.py", line 74, in get
    fileutils.rsync(self.source, dest)
  File "/usr/lib/python2.7/dist-packages/codetree/fileutils.py", line 26, in rsync
    raise FileManipulationError("Only files and directories can be copied")
FileManipulationError: Only files and directories can be copied

I was able to work around this by prepending /home/stg-ue-error-tracker/ to the command line option mojo-error-tracker.