Bug fix in nilearn/group_sparse_covariance.py in function 'group_sparse_covariance_path': test covariances are now only computed if 'test_subjs is not None', i.e., if test_subjects are given. Previously this returned a ValueError since the covariance of a NoneType object was computed.
Merge pull request #111 from rphlypo/master

Bug fix in nilearn/group_sparse_covariance.py