factor: add a test for a num-prime issue

[sylvestre]

No description provided.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/date/resolution is no longer failing!
Congrats! The gnu test tests/basenc/bounded-memory is now passing!
Congrats! The gnu test tests/expand/bounded-memory is now passing!
Congrats! The gnu test tests/tail/tail-n0f is now passing!

[codspeed-hq]

Merging this PR will improve performance by 15.21%

⚡ 2 improved benchmarks
✅ 286 untouched benchmarks
⏩ 42 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	shuf_input_range[1000000]	92.6 ms	83.9 ms	+10.36%
⚡	Memory	shuf_input_range[1000000]	8.9 MB	7.7 MB	+15.21%

---

_{Comparing sylvestre:factor (eeae106) with main (74b8924)²}

Footnotes

1. 42 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (d3639db) during the generation of this report, so 74b8924 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩