pkgbase: report errors via metalog reader exit status

[emaste]

I'm a bit of a lua novice, so if there's a canonical way to do this please let me know

[kevans]

tools/pkgbase/metalog_reader.lua

89

Drop the assignment, it'll default to nil which is a falsey value

159

return #duperr or #inodeerr, perhaps

[emaste]

Perhaps more idomatic lua from kevans

[emaste]

tools/pkgbase/metalog_reader.lua

159

Or actually return #duperr > 0 or #inodeerr > 0

[emaste]

fix truthiness confusion