Update comment. Should have been in commit b5faaea.
Use list* style patterns, i.e. `xs ...` => `. xs`

Faster on older Rackets. More concise.
Commit d6f3141 relaxed the prompt regexp too much.

Need to require at least one space following the >.

This change broke racket--get-namespace-symbols: Its output would stop
going to the redirected output buffer and start spilling into the REPL
buffer instead.