This fixes a bug that Chris Mason found. As for a test case, I can't think of one. It's a very weird case. Basically, if there is a file listed as changed in the changelog entry, but not showing up in any of the associated manifest entries, hg would abort when trying to create a changeset. Now it just decides the file must not have any versions relevant to the changeset.

default = "changelog"
header = header-rss.tmpl
changelog = changelog-rss.tmpl
changelogentry = changelogentry-rss.tmpl
filelog = filelog-rss.tmpl
filelogentry = filelogentry-rss.tmpl