Refreshing feeds offline

When trying to refresh feeds (feed toolbar or context menu) with a disabled internet connection, I experience two behaviours:

1. Refreshing ends almost immediately.
http://newsfox.mozdev.org/rss/rss.xml

2. Refreshing only ends after the feed refresh timeout.
http://newsrss.bbc.co.uk/rss/newsonline_uk_edition/uk_politics/rss.xml

I tried to refresh feeds without an active internet connection to see if I get a warning or not. Actually, I do not, thus I have every reason to believe that the refreshing was successful. This impression is even stronger if there are deleted articles, which disappear exactly the way they should.

NewsFox 1.0.3b2