CLI tool does not use alphanumeric encoding on appropriate strings in some circumstances

[jkopczyn]

I have not fully investigated the circumstances where this happens, but I have a minimal pair of examples, below. In at least the case where a purely monocase alphanumeric string is given, with High error correction level set, the tool encodes it with 8-bit encoding rather than alphanumeric coding as it should, resulting in a significantly larger grid image than necessary.

This is probably not of significant impact in normal uses, but I'm using it to set up a puzzle where the alphanumeric version-6 33x33 grid rather than the 8bit version-8 41x41 would be significantly easier to fine-tune, and I need the high error correction level because I expect the fine-tuning to require corrupting the grid, possibly quite a lot. And it is, if I understand everything correctly, failing to correctly implement the QR Code encoding spec, which may matter in some other circumstances.

Examples:

$ qrencode -l H -i --verbose -o smaller.png "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOP"
File: smaller.png, Version: 8
$ qrencode -l H -i --verbose -o smaller.png "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNO"
File: smaller.png, Version: 7

I have personally verified that the resulting images are the sizes indicated and decode properly but can provide them if requested.