Error-path reference leaks in `Repository.listall_branches` and `Tree.diff_to_index`

[K-ANOY]

Two functions leak an owned object on one early-error path that returns directly instead of going through the cleanup they already have a few lines below.

Repository_listall_branches_impl()

File: src/repository.c, line 1424

list = PyList_New(0);
if (list == NULL)
    return NULL;

if ((err = git_branch_iterator_new(&iter, self->repo, list_flags)) < 0)
    return Error_set(err);          /* list leaked */

Every other error exit in this function releases the list — the loop body jumps to error:, and the post-loop failure does Py_CLEAR(list) — so this one return is the odd one out.

Suggested fix:

if ((err = git_branch_iterator_new(&iter, self->repo, list_flags)) < 0) {
    Py_DECREF(list);
    return Error_set(err);
}

Tree_diff_to_index()

File: src/tree.c, line 269

PyObject *py_idx_ptr = PyObject_GetAttrString(py_idx, "_pointer");
if (!py_idx_ptr)
    return NULL;

/* Here we need to do the opposite conversion from the _pointer getters */
if (PyBytes_AsStringAndSize(py_idx_ptr, &buffer, &length))
    goto error;

if (length != sizeof(git_index *)) {
    PyErr_SetString(PyExc_TypeError, "passed value is not a pointer");
    goto error;
}

index = *((git_index **) buffer);

/* Call git_diff_tree_to_index */
if (Object__load((Object*)self) == NULL) { return NULL; } // Lazy load

The two checks above it use the error: label, which does Py_DECREF(py_idx_ptr); the lazy-load failure returns directly and leaks py_idx_ptr.

Suggested fix:

if (Object__load((Object*)self) == NULL) { goto error; } // Lazy load