#472 Node.previous_sibling is broken

[flying sheep]

It doesn’t work as advertised, as it never returns None.

def previous_sibling(self):
    """Return preceding sibling node or ``None``."""
    try:
        return self.parent[self.parent.index(self)-1]
    except (AttributeError, IndexError):
        return None

This means that when self is the first child, i.e. self.parent.index(self) == 0, then self.parent[-1] is returned. The last child, not None. If len(node.parent) == 1, that means node.previous_sibling() is node.

This in turn means that the HTML writer for citation elements will emit broken HTML, see https://github.com/mcmtroffaes/sphinxcontrib-bibtex/issues/329

This is pretty severe since it leads to broken HTML markup and therefore completely broken page layout.

[flying sheep]

Ah, it’s been fixed in https://sourceforge.net/p/docutils/patches/195/ / v0.20

[Günter Milde]

This is a duplicate of [patches:#195], fixed in Docutils 0.20.
Thanks for reporting, anyway.