Bug: git log changes output depending on how the output is used

I noticed that the piped output still prints the (HEAD -> ) :



git log --pretty=format:"%d*%B" --decorate-refs='refs/tags/*'

*bar
(tag: "123")*foo





git log --pretty=format:"%d*%B" --decorate-refs='refs/tags/*' > tmp.tmp

(HEAD -> branch)*bar
(tag: "123")*foo



I would expect the output that is printed to console, not what's
present in tmp.tmp