That is a good point, except I don't believe the value needed to expose this bug is a "too-high limit" (as the documentation calls it).  I set it to 100100 for convenience, but in practice even a value of 17000 is more than enough to expose the bug on my system (it occurs at around 16500).  For my friend using Windows, a value as low as 4000 suffices, which I don't think anyone would argue is unreasonably high.

The default value of 1000 is extremely low, and is intended to catch recursion bugs in programs that are not expected to recurse very deeply.  For a program that genuinely needs recursion, I don't think a value of 20000, or even 100000, is unreasonable given today's typical memory sizes (and when I run my failing case, the memory usage is so low as to be inconsequential).  By my interpretation, these limits should be well within the range that Python can handle.

It seems likely to me that in this case, the problem isn't due to any kind of system limit, but is rather the result of a logical error in the implementation which is somehow exposed by this test.  Hopefully a developer will take advantage of this test case to fix what I believe is a serious bug.