(Trailing?) context of a section does not get folded

[hotsphink]

Description of the bug

When I fold a section, it removes the changed lines from view, and usually the leading context, but usually leaves the trailing context of those changes visible. Actually, it seems very inconsistent; I'm not sure when it chooses to collapse things and when not.

Expected behavior

Folding a file seems to always fold the whole file, as expected.

I would expect folding a section to hide both leading and trailing context if it is not shared with a neighboring unfolded section.

Actual behavior

Consider

If I fold the section 1/6, I get

Notice how the leading context is gone (good), the one changed line is gone (good), but the trailing context (lines 236..238) is still there.

Folding section 2/6 (with the first still folded) does the same thing, which turns out to be correct in this case:

lines 236..238 are now gone, the ellipsis is gone, lines 1619..1621 are gone. The changed lines are gone. The trailing context is still there, but that's ok this time because it's shared with the next section.

Folding section 3/6

fails in the same way as 1/6.

Version of rustc

No response