I was editing this question on russian.SE where the OP was asking about the meaning of a Russian poem. As the poem itself wasn't formatted properly, I wanted to fix the line breaks to make it easier to read. In the process of doing so, I essentially broke the poem down with the line breaks and added
<br/>, so that it would look like so:
Line 1<br/> Line 2<br/> Line 3<br/> Line 4<br/> ...
Then I highlighted the whole poem and clicked the "blockquote" button. I expected the block to just be indented with
>, however besides that, all line breaks were deleted and the text became
> Line 1<br/> Line 2<br/> Line 3<br/>Line 4<br/>
While this produces the output I want, it's still messing up the original text making it more difficult for anyone who may want to edit the post later. I ended up having to do this manually for each of the lines.
I don't think changing the content on click of a formatting button is the right behaviour.