Avoid errors from selecting "no selection" on multilink (issue2550722). As discussed in issue 2550722 there are various cases where selecting "no selection" on a multilink can result in inappropriate errors from Roundup: * If selecting "no selection" produces a null edit (a value was set in the multilink in an edit with an error, then removed again, along with all other changes, in the next form submission), so the page is rendered from the form contents including the "-<id>" value for "no selection" for the multilink. * If creating an item with a nonempty value for a multilink has an error, and the resubmission changes that multilink to "no selection" (and this in turn has subcases, according to whether the creation then succeeds or fails on the resubmission, which need fixes in different places in the Roundup code). All of these cases have in common that it is expected and OK to have a "-<id>" value for a submission for a multilink when <id> is not set in that multilink in the database (because the original attempt to set <id> in that multilink had an error), so the hyperdb.py logic to give an error in that case is thus removed. In the subcase of the second case where the resubmission with "no selection" has an error, the templating code tries to produce a menu entry for the "-<id>" multilink value, which also results in an error, hence the templating.py change to ignore such values in the list for a multilink.

=======================================================
Roundup: an Issue-Tracking System for Knowledge Workers
=======================================================

INSTANT GRATIFICATION
=====================

The impatient may try Roundup immediately by running demo.py from
the source directory::

   python demo.py

This will create new tracker home in "demo" subdirectory and start
server. To reset demo instance::

   python demo.py nuke


Tracker Home
=============
"Tracker Home" is main concept when starting with Roundup. It is
directory where all your tracker data is stored. This directory is
created every time when new tracker is initialized and includes
tracker configuration, database, template, schema and extensions.


Installation
============
Please see "doc/installation.txt"


Upgrading
=========
Please see "doc/upgrading.txt"


Usage and Other Information
===========================
Start with the index.txt file in the "doc" directory. These
documentation files are written in reStructedText, which can be
converted into HTML format. If you have Sphinx installed, you can
do this by running::

   python setup.py build_doc

Resulting HTML files will be in "share/doc/roundup/html" directory.


For Developers
==============
To get started on development work, read the developers.txt file in
the "doc" directory.


License
=======
See COPYING.txt