Overview:

In Krita 3.1.4, the Save As and Export dialogs can silently overwrite an existing file if you let it automatically add the file extension. It seems to happen regardless of the file type, as long as the full filename (including extension) is the same as an existing file.

Steps to Reproduce:

1. Create a file named foo.kra somewhere. The contents don't matter.
2. Open Krita and create a new document.
3. Go to the File menu and click either Save As or Export.
4. Navigate to the directory containing foo.kra.
5. Select the "Krita document" file type and type "foo" into the filename box.
6. Click "Save".

Expected Results:

Krita adds the file extension automatically, then sees that a file with that name already exists and asks me whether I want to overwrite it.

Actual Results:

Krita adds the file extension automatically and overwrites the existing file without prompting.

Build Date & Platform:

Krita 3.1.4 (built from source) on Ubuntu 16.10.