What I expected to happen was...:
Files with no name, only an extension, fail to load.
 
What actually happened was...:
Instead, they load with IDs such as foo: and foo:bar/
 
Steps to Reproduce: # Create or download a datapack with the following functions:

1. 1. data/foo/functions/.mcfunction
   2. data/foo/functions/bar/.mcfunction
2. Load the datapack, noting the number of functions includes those nameless files.
3. Note that you can run the following commands:
   1. /function foo:
   2. /function foo:bar/

I acknowledge it's possible this is intended, but it seems too weird and unexpected.