Filter out stackoverflow links too

Author: dstansby

check-links.py

@@ -11,9 +11,10 @@
 status_codes = [pdfx.downloader.get_status_code(ref.ref) for ref in refs]
 
 broken_links = [(ref.ref, code) for ref, code in zip(refs, status_codes) if code != 200]
+# It seems that Twitter and stackoverflow do not respond well to the link checker and throws a 400
+broken_links = [b for b in broken_links if not ('twitter.com' in b or 'stackoverflow.com' in b)]
 
-# it seems that Twitter does not respond well to the link checker and throws a 400
-if all(['twitter.com' in url for url, _ in broken_links]):
+if len(broken_links) == 0:
     sys.exit(0)
 else:
     print('Broken links:', broken_links)