def fix_multi_T1w_source_name(in_files):
    """
    Make up a generic source name when there are multiple T1s

    >>> fix_multi_T1w_source_name([
    ...     '/path/to/sub-045_ses-test_T1w.nii.gz',
    ...     '/path/to/sub-045_ses-retest_T1w.nii.gz'])
    '/path/to/sub-045_T1w.nii.gz'

    """
    import os
    from nipype.utils.filemanip import filename_to_list
    base, in_file = os.path.split(filename_to_list(in_files)[0])
    subject_label = in_file.split('_', 1)[0].split('-')[1]
    return os.path.join(base, 'sub-%s_T1w.nii.gz' % subject_label)
