This allows something like the following local.lua to install a filter
to implement its own notion of hidden BEs using a naming convention of
a leading dot to hide them:

• file: /boot/lua/local.lua

local core = require("core")

local function be_hide(be)

if core.isSingleUserBoot() then
    -- All BEs are accepted for single-user
    return true
end

local name = be:match("/([^/]+)$")
if not name then
    -- Accept malformed BEs, for whatever reason
    return true
end

return name:match("^%.") == nil

end

core.bootenvFilter(be_hide)

• EOF

Requested by: Marek Zarychta