Many years of experience have taught me that fields holding data being able to hold any sequence of bytes is normal (and in the case of string data, anything except 00), so this didn't surprise me too much; in fact, it's usually when something is unusually restrictive that it becomes notable.
I was honestly more surprised at how much data I could fit in that field. Git itself doesn't appear to have any limit at all, though GitHub doesn't allow more than a few dozen megabytes.
