codespell mysteries explained

[Douglas Bagnall]

I was trying to run

  codespell $(git diff origin/master --name-only)

to catch my typos before CI does, but they seem to find completely 
disjoint sets of complaints. That is, *none* of the local codespell 
issues were raised by CI, and vice versa.

Locally I have "codespell 2.1.0" on Ubuntu 22.04. It doesn't care when I 
write "secuirty" in a C comment, while CI does. And it does say a lot of

  python/samba/tests/sddl.py:193: BA ==> BY, BE

which CI doesn't mention.

Adding "ba" to .codespellignore makes the "BA" complaints disappear. I 
would prefer to just ignore uppercase "BA", but when the manpage says

   Words are case sensitive based on how they are written in
   the dictionary file

it is saying you *can't* ignore uppercase only if the codespell 
dictionary[1] doesn't contain a "BA->..." line. It doesn't.

[1]/usr/lib/python3/dist-packages/codespell_lib/data/dictionary.txt

The local dictionary also doesn't contain "secuirty". The upstream 
version does, and it doesn't have the "ba". So that explains everything.

When I started this email, it was going to be along the lines of "WTF am 
I missing", but it turns out to be quite simple. If you have an ancient 
OS (from, say, last year) don't expect to be able to replicate codespell 
CI locally.

Douglas