def get_module_source_path(modname, basename=None):
    """Return module *modname* source path
    If *basename* is specified, return *modname.basename* path where 
    *modname* is a package containing the module *basename*
    
    *basename* is a filename (not a module name), so it must include the
    file extension: .py or .pyw
    
    Handles py2exe/cx_Freeze distributions"""
    srcpath = get_module_path(modname)
    parentdir = osp.join(srcpath, osp.pardir)
    if osp.isfile(parentdir):
        # Parent directory is not a directory but the 'library.zip' file:
        # this is either a py2exe or a cx_Freeze distribution
        srcpath = osp.abspath(osp.join(osp.join(parentdir, osp.pardir),
                                       modname))
    if basename is not None:
        srcpath = osp.abspath(osp.join(srcpath, basename))
    return srcpath