If I call
git clone --shallow-since 2019-09-20 https://github.com/emacs-mirror/emacs.git
I cannot access commit 56985dd8a6, although it is from 2019-09-21. Git stops at the red line in the following screenshot:
I don’t understand the algorithm here. While the next commit is of 2019-09-17, so one could assume that it stops when it hits the first too old commit, there was already one of 2019-07-10 before that. So, what are the rules of --shallow-since
?