Importing .db modifies the source file (1.5.4)

If I import a .db file into CN 1.5.4, it modifies that file. This is no way right.

Reproduce:

1. Create two portable CN installations: 1.5.3 and 1.5.4
2. Create a .db in CN 1.5.3, close CN
3. Import that .db in CN 1.5.4
4. Run CN 1.5.3

5. Get an error:

This is getting even more interesting in the following scenario:

Run CN 1.5.3
Run CN 1.5.4, import file that is opened in CN 1.5.3.

The file is changed, but the running CN 1.5.3 is still able to write into it. It will not be able to run again, but if we open 1.5.3's .db file in 1.5.4, we will see the new entry.

I think importing should not touch the source in any way.