spider a github markdown website for broken links

for the few times I have done this wget worked fine, not on github: wget -r -nv --spider http://ift.tt/2gUy1AD -o log.txt

and a bit of grep

I am trying to do this on the http://ift.tt/2gUy1AD website to find and fix broken links

robots.txt: Allow: ///tree/master

and wget stops after reading robots.txt:

wget -r -nv --spider http://ift.tt/2gUy1AD 2017-11-02 10:30:37 URL:http://ift.tt/2gUy1AD [135752] -> "http://ift.tt/2ilJ9qL" [1] 2017-11-02 10:30:38 URL:http://ift.tt/1itr0Pr [30486] -> "http://ift.tt/1PSSaOY" [1] Found no broken links.

FINISHED --2017-11-02 10:30:38-- Total wall clock time: 2.5s Downloaded: 2 files, 24K in 0.4s (57.0 KB/s)

Any ideas? when I search for spider and github I get lots of projects and not much else