rss_fetch.inc (and MagpieRSS) do not belong to b2evo itself.
It looks like a custom script and maybe it does not work with the new b2evo version.

I wonder where you found the method you use to include magpierss in b2evolution? If it was the hack I did there's a thread for it somewhere, and I can tell you the hack as-written still works in version 1.8.7 of b2evolution. I did not test it with each new release and can't recall what version I released it for, but I'm thinking if it worked back then and works now it will probably work with all versions between. For sure it was back in the 0.9.0.* days when I initially did my hack.

http://forums.b2evolution.net/viewtopic.php?t=2258&highlight=magpie

this one, perhaps.

Yes indeed that be the one! When I wanted it for my 187 app I had to find it here because I don't have a copy of it locally anymore. I can't say if I ever incorporated the "there's a big image" fix or not, but I did fix that thread to not require a left-right scroll bar anymore.

(code tag will wrap a line, php tag will not seems to be the root cause)

Thanks VERY much guys, I'll take a look!