Incorrect test count when nesting describe

[luttje]

The test counts are incorrect, which becomes obvious when nesting describes

Reproducing

Our tests/init.lua without describe:

require "tests/all"

Results in 30 skipped, 188 passed, 218 total

With an extra describe around it:

describe('all tests', function()
    require "tests/all"
end)

Results in 30 skipped, 138 passed, 168 total