output wrong data if add/remove strings

[SailorMax]

GitBlame ignore new line shifts in modified file.

Steps:

1. open document modify history has few people, for example:
   line 1 by user A
   line 2 by user B
   line 3 by user C
2. put cursor in end of line 1 and press Enter
3. check owners of lines 1-4

Expected:
line 1 by user A
line 2 (empty) has no user
line 3 by user B
line 4 by user C

Actual:
line 1 by user A
line 2 (empty) by user B
line 3 by user C
line 4 has no user