Liquid Exception: "\xEF" from ASCII-8BIT to UTF-8 in getstarted/demos/index.html

jekyll 2.5.2 | Error:  "\xEF" from ASCII-8BIT to UTF-8

I am on this ruby version:

ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-darwin13.0]

Or am I the only person, seeing this ? 

Thanks,

Matthias