Renaming a file while copying makes the copy fail
If you have a big file (e.g. 12 GB), and you copy it, and you rename the duplicate version BEFORE the copying finished, the copy will fail with an error message.
For instance, if you have "a.db", and you copy it, the default filename will be "a (copy).db".
Then nautilus starts the copy and shows progress on the upper right corner.
If you rename "a (copy).db" into "b.db", at the end the copy will fail with an error message.