acme doesn't always clear the right margin to compensate for the different amount of right-margin slop due to different character widths. in this case ">" is very wide and won't fit in the space that "n" did. so the n is mistakenly shown where it shouldn't be.
between the two pngs, the text "has gone" was cut. hget http://www.quanstro.net/plan9/acmebug/w0.png|png hget http://www.quanstro.net/plan9/acmebug/w1.png|png - erik