If I edit a file with IDLE, save it, and successfully run it (perhaps to test it), then when I edit a second file that imports the first, I expect the import to work. It does not always (see #10828).
Import is part of the core definition of the language. Unicode identifiers are supposedly part of Python3. Given the existence of <identifier>.py in the current directory, 'import identifier' should work. If it does not, the 3.1 message '<identifier> not found' is more truthful than the current 'no module named <identifier>', when there is one.
The doc says "identifier ::= (identifier ".")* identifier". As long as that is not true, some indication of the restriction that most people can understand would be nice. (And I suspect that a majority of Windows users, at least in the US, have no idea of what an 'ANSI code page' is.)