[Rails 3.2] REXML::ParseException ... invalid byte sequence in UTF-8

when parsing an xml response ( UTF-8 encoding) I get a parsing error

response =>
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<rss xmlns:opensearch=
\"http://a9.com/-/spec/opensearch/1.1/\" xmlns:dc=\"http://purl.org/dc/
elements/1.1/\" version=\"2.0\">\n <channel>\n <title>link:http://
lvh.me:3000 - Google Recherche de blogs</title>\n <link>http://
www.google.com/search?q=link:http://lvh.me:3000&amp;tbm=blg</link>\n
<description>Aucun document ne correspond aux termes de recherche sp
\xE9cifi\xE9s (&lt;b&gt;link:http://lvh.me:3000&lt;/b&gt;).</

\n <opensearch:totalResults>0</opensearch:totalResults>

\n <opensearch:startIndex>1</opensearch:startIndex>\n
<opensearch:itemsPerPage>10</opensearch:itemsPerPage>\n </channel>\n</

"

parse_rss(response)

def parse_rss(body)
      xml = REXML::Document.new(body)
REXML::ParseException Exception: #<REXML::ParseException:
#<ArgumentError: invalid byte sequence in UTF-8>

which seems to be raised by the <description> tag with a french text
using accentuated characters... like sp\xE9cifi\xE9s

is it an REXML bug ? ( in this case I may switch to Nokogiri...)
or did I missed any mandatory parameter in my request ?

thanks for your feedback

[SOLVED] found the answer here :
http://yehudakatz.com/2010/05/05/ruby-1-9-encodings-a-primer-and-the-solution-for-rails/
.. I forgot to mention I am using Ruby 1.9.3 .....

so

xml =
REXML::Document.new(body.force_encoding("ISO-8859-1").encode("UTF-8"))

is the right way to handle the response