> py> str(timedelta(0, -1))
> '-1 day, 23:59:59'> ..
> Does anyone remember the rationale for this behaviour?
I don't recall any better rationale than what I wrote in the docs: "String representations of timedelta objects are normalized similarly to their internal representation."
> Is it open to debate or is it now cast in stone?
I think the barrier for changing str() is lower than that for changing repr(), but I would be against any changes in this area. (I may have had a different view if ISO 8601 syntax for timedeltas was not so ugly. :-)