a weird bug with pack & unpack

[spir <denis.spir@...>]

Hello,

Sorry to bother you with such an unimportant issue, but it drives me crazy:

I have a set of everyday tools, mainly tiny funcs one of which uses table pack & 
unpack. This func works very fine, it is exhaustively tested --locally. When I 
use it from other program files, I often get an error telling that Lua does not 
find the field (or global) 'pack' --
_sometimes_; and all works fine, _sometimes_. If I replace pack with a 
workaround, then I get the same issue about unpack. I cannot find any logic.

The same happens (works or not) whether pack & unpack are denoted on the table 
'table' or under aliases (just the 'table.' prefix removed). I have checked 
several times that nothing in my present project files uses such names, or 
modifies table, except for adding a few 'methods' like table copy. Dunno. I'm 
highly frustrated of not getting the logic and annoyed because the func in 
question is a very practicle debugging tool I constantly use.

Lua 5.2.1 on linux (lubuntu)

Thank you,
Denis