[Lazarus] Error when saving a new project: Unit.pas should not be used as file name

[Jürgen Hestermann]

When I create a fresh application, save it to an empty directory, then I 
am asked for two file names ("project1.lpi" and "Unit1.pas").
But the "Unit1.pas" name is not accepted and I get a warning saying 
(translated from german):

It looks like a Pascal file.
It is recomended to use non-capital letters for file names to avoid 
problems.
Rename it?

But the name was chosen by Lazarus itself!
Why did it use a file name that is not recommended
and then ask the user whether it should be renamed?