Release notes for 0.7.9:

...
- loosened the detection of issue cross-references in
messages
...

Now all of the following strings are rendered as
hyperlinks:

issue40
issue 40
Issue40
Issue 40
Issue   40
issue  40

Those starting with a lower case letter work. Those
starting with an upper case letter produce the
following exception:

KeyError: 'There is no class called "Issue"'

(Roundup 0.7.11, Windows, Python 2.3, pysqlite backend)