euscan: don't fail if robots.txt can't be read

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>

pym/euscan/helpers.py

@@ -416,7 +416,7 @@ def urlallowed(url):
 
         setdefaulttimeout(timeout)
 
-    return rp.can_fetch(CONFIG['user-agent'], url) if rp else False
+    return rp.can_fetch(CONFIG['user-agent'], url) if rp else True
 
 
 def urlopen(url, timeout=None, verb="GET"):