Duplicate line does not work correctly on first line of document or on blank second line

[jeremypw]

What Happened?

Trying to duplicate the first line of a document using the shortcut <Ctrl>D failed. When the second line contained text it was duplicated. If the second line was blank then both it and the third line was duplicated.

Steps to Reproduce

1. Create a new document containing just the line number on each line (1,2,3,4 ...).
2. Place the cursor on line 1 and press <Ctrl>D
3. Observe that the document now contains five lines with two lines with "2" (1,2,2,3,4 ...)
4. Create a similar document containing a blank second line (1, _, 2,3,4, ...)
5. Place the cursor on line 1 and press <Ctrl>D
6. Observe both 2nd and 3rd line duplicated (1, _, 2, _,2,3,4)

Expected Behavior

Only the line on which the cursor is place is duplicated.

OS Version

6.x (Odin)

Software Version

Compiled from git

Log Output

No response

Hardware Info

No response