We use a variant of CommonMark that renders
a
b
c
as
a
b
c
This is discussed in detail here: Default line break handling is inconvenient
My expectation is that if this “option” is enabled any sequence of inline HTML elements on lines by themselves would behave the same way as the text.
@codinghorror for the record I did “fix” this in Discourse. But I feel that we got to glue some special semantics to HTML inlines if you have the “newline”=<br> option enabled.