The Limbo language predated Go by over a decade, and is, in fact, a predecessor of Go. I think its creation and use in this system makes more sense in the context of 1995 when it was initially created.
Weird side note: Renee French did both the Plan 9 and Go mascot designs as well.
And to the further above, there are other languages and compilers supported on Plan 9/Inferno. Like Go.
Source: Penn's radio show where Rob and Renee were each guests at different times.
When I try searching for "golang" and "limbo X" (where X = history, or comparison, or..., or...) it looks like the popularity of golang swamps any pages that might compare Go and Limbo.