I'm still having this issue as of 5/28/2020. I've narrowed down the issue to here:

Specifically, Go's exec.Command will treat spaces in parameters as different parameters, so they must be escaped or quoted if they have spaces.

I do not have the capabilities (right now) to get Hugo building on my machine, but I believe the simplest fix will be somehow escaping the string when passing it to exec.Command.

I believe, but cannot be certain, that this line should fix this issue:

configFile = `"` + configFile + `"`

This was closed as stale in #6283, but I think my solution should fix the problem.