Be more robust when rendering wiki text containing changeset TracLinks (for example, this can cope with the repository being unavailable).
Be more robust when rendering wiki text containing changeset TracLinks (for example, this can cope with the repository being unavailable).

git-svn-id: eda3d06fcef731589ace1b284159cead3416df9b@5399 af82e41b-90c4-0310-8c96-b1721e28e2e2

jun66j5/trac-ja,walty8/trac,jun66j5/trac-ja,walty8/trac,netjunki/trac-Pygit2,walty8/trac,netjunki/trac-Pygit2,netjunki/trac-Pygit2,walty8/trac,jun66j5/trac-ja,jun66j5/trac-ja