[army]

That doesn't seem that esoteric to me: in general the problem is that repr() can result in execution of arbitrary code, and that there's no way to cleanly and reliably terminate arbitrary code. This includes Python code: it's possible to terminate it at an arbitrary point, but that leaves things in an indeterminate state.

I think it's pretty important that you shouldn't add features with unpredictable behaviour into the core of the language, particularly into error handling code.

[moe]

It's esoteric because in reality it's the kind of bug that never happens. And if it happens it's trivial to identify the cause; "Oh, it hangs in the middle of a strack-trace, what could it possibly be...".

Why would your code contain repr()-functions that trigger "unpredictable behavior" to begin with anyway?