Line numbers mysteriously disappear

[bendavis78]

I was finally able to reproduce this using the following steps:

1. Open a new file
2. Type print("one"), press Enter
3. Type print("two"), press Enter
4. Type print("three")
5. Save the file (a newline is automatically added for some reason)
6. Place cursor on last line and press Backspace to delete the line
7. Place cursor at end of line 2 and press Enter

The result is this:

[serwy]

What version of Python are you using? With 3.7 on Linux, I can not replicate the bug.