git - GitHub - why two lines are marked as different without any visible differences? -

here's commit cba438 on github.

as can see line #1 in index.html marked changed:

but can see there's no single changed character. github or git? bug or hidden character changed?

yes, there hidden character there, utf8 bom.

$ git show cba438:index.html | od -c | head -1 0000000 357 273 277   <   !   d   o   c   t   y   p   e       h   t   m $ git show cba438~1:index.html | od -c | head -1 0000000   <   !   d   o   c   t   y   p   e       h   t   m   l   >  \n 

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related question: what's different between utf-8 , utf-8 without bom?