"I checked my Windows registry entry for the .leo class, and I have it as leo_auto_file. I don't remember setting that up, but the shell/open/command entry points to Leo's git directory on my machine, so it must have been me that did it. It's just that leo_auto_file doesn't seem like the kind of name I would have made up. Funny..."
XXXX_auto_file associations are created by Windows when a person 2x-clicks on an unknown filetype and then selects "Always use this app to open ..."
From the command line they can be managed with
assoc and
ftype commands.
-matt