I do not think this would be an FAQ any more. In the spirit of "FAQ's are almost bugs", let me remove this "Infrequently Asked Question"
bye-bye, wrap=FALSE, you are a first-class citizen now :heart:
from @kbroman's example, I realized that the pipes did not work in markdown tables, and they have to be escaped to the HTML entity &#124;

see kbroman/knitr_knutshell#1