lua get_meminfo got broken somewhere along the line in the trunk
The original implementation (as documented in the comment and still present in the release branch) lets you get meminfo for *either* the canon heap or the exmem heap if exmem is enabled. If neither is specified, you get whichever one CHDK allocates from. If you ask for exmem when exmen is not enabled it returns false.
In the trunk, it just gives you whichever one CHDK allocates from, and never returns false.