I could reproduce this, but I don't know if this is really a bug.
(I never heard of protecting spaces with angle brackets.)
Actually, it's right there in section 4.3 of the manual, last
sentence: "if you need to remove ambiguities about the end of the
link, enclose them in angular brackets. "
You do not have to protect spaces, because the URL is surrounded by
the
square brackets. I could only insert angle brackets into a link by
editing it manually; when you edit a link with C-c C-l and enclose
the
URL in angle brackets, Org will automatically remove them.
Thanks, both these methods work -- although I still think it would be
nice if org mode could properly handle angle brackets inside square
ones; the motivation here is that often I just paste in file paths
instead of using C-c C-l, and then I have to use angle brackets to
deal w/ spaces; if I later want to change it to an annotated link, it
would be nice not to have to strip the angle brackets before wrapping
it in square ones...