some debug for image downloading

screenless/bureau/bureau.py

@@ -386,11 +386,13 @@ class Bureau(object):
 
         # use an URL fetcher that waits 30s instead of 10s
         def slowfetch(url, timeout=30, ssl_context=None):
+            if len(url) < 50:
                 print("fetching", url)
             import time
             start = time.time()
             ret = weasyprint.default_url_fetcher(url, 30, ssl_context)
             elapsed = time.time() - start
+            if len(url) < 50:
                 print("fetched", url, "in", elapsed)
             return ret