segfault

import svn.core    import svn.client    pool = svn.core.svn_pool_create(None)   ctx = svn.client.svn_client_create_context(pool)    revision = svn.core.svn_opt_revision_t()revision.kind = svn.core.svn_opt_revision_headsvn.client.svn_client_checkout("https://a", ".", revision, True, ctx, pool)