I have no idea if this is a potentially exploitable security issue or just a nit pick. In this comment:
yep! ;-) btw that's A._B._and_C. If you just past the link without the brackets, the SE url parser (for lack of a better name) thinks you made a mistake and truncates the link before the final period: https://en.wikipedia.org/wiki/A._B._and_C.
I point out that a bare url (from Wikipedia) that ends in a period is truncated, and sends you to the url without the period.
This automatic behavior produces a bad link when a good (but bare) link is pasted.
Is there any way to avoid this? I don't think it rises to the level of a bug, but is the auto-dropping of the trailing period in the url done by-design?