The Return key stopped breaking paragraphs at the wrong spot

A bug DW reported earlier but couldn't reproduce finally showed itself: paste a chunk of text that includes a link, put the cursor somewhere later in the text, press Return -- and the break landed at the link instead of the cursor, tearing the link out onto its own line. The trick to reproducing it: it only ever happened on the first Return after that kind of paste, never again in the same post -- which is exactly what made it so slippery. Now the break lands where the cursor is, and links stay in their sentences. (Theme v0.5.339.)