[bugzilla] Use dont_decode in web.get

lxml refuses to parse unicode strings if the string contains an encoding
decleration. This means the bugzilla module has been broken since the
introduction of the decoding capability of web.get and nobody noticed.

This commit fixes that issue.

bugzilla.py

@@ -55,7 +55,7 @@ def show_bug(bot, trigger, match=None):
     if domain not in bot.config.bugzilla.get_list('domains'):
         return
     url = 'https://%s%sctype=xml&%s' % match.groups()
-    data = web.get(url)
+    data = web.get(url, dont_decode=True)
     bug = etree.fromstring(data).find('bug')
 
     message = ('[BUGZILLA] %s | Product: %s | Component: %s | Version: %s | ' +