repl-temp-000.elm in error messages

[rtfeldman]

It's a bit distracting to see repl-temp-000.elm as the filename in error messages:

-- PARTIAL PATTERN ------------------------------------------- repl-temp-000.elm

This pattern does not cover all possible inputs.

Would be better if it just had more dashes, e.g.

 -- PARTIAL PATTERN -------------------------------------------------------------

This pattern does not cover all possible inputs.