[BUG] Strange case sensitivity when matching minions

salt 'us*' test.ping matches minions that start with 'us' and 'US' (both upper and lower case).
salt 'US*' test.ping only matches minions that start with 'US' and not 'us' (only upper case).

In our system, Windows machines are all upper-case...so I'm thinking maybe Windows is the culprit even though the salt master is running on a 'nix system.

I can work around this by running salt -E 'us.*' or salt -E 'US.*'.

Expected behavior
I would expect minion matching to be case-sensitive and consistent with other salt programs like salt-key.
salt-key -a us* only matches lower-case.
salt-key -a US* only matches upper-case.