When following the Contributing section of the manual in my home directory, I was unable to use the built guix to do anything as I hit upon a message saying "error: failed to run download program '/home/truby/src/guix/scripts/guix': Permission denied?"
After some debugging I realised this was because my home directory was not world readable. I think to avoid other people having this problem it might be worth mentioning in the manual that the source directory needs to be readable by the guixbuild group for the users in that group to be able to actually build anything. (In hindsight, this seems obvious to me. But it wasn't when I first ran through that section of the manual!)
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