I've turned off the ability to browse the Plan 9 sources
on our external web site, because it was being overwhelmed
by web crawlers. Each access spawned a command that ran
multiple seds, etc. I've added restrictions to our robots.txt
to prevent crawling the sources and instructed google to
crawl more slowly.

I hope that these restrictions are temporary and that some or
all can be lifted after the crawlers see the new robots.txt.