ZTK bugs are tracked in individual projects (one per package) using Github’s bug trackers.
TODO comments in the source code are not
considered bugs and therefore cannot block releases. Consider adding a
bug in addition to the comment. If something is really broken and you
want to indicate it with
XXX, consider instead not checking this
into the trunk of a project but into a separate working branch.
Historically, bugs have been tracked with the Zope 3 project (https://bugs.launchpad.net/zope3).
Even longer ago, Zope 3 used its own bug tracker (which lived at http://www.zope.org/Collectors). Those were imported into the Launchpad bug database and have aliases of the form “zope3dev-NNN” where “NNN” is the old bug number, so they can be retrieved by searching for these on Launchpad.