Omits a single additional inserted line

[AndydeCleyre]

Hi, and thanks! I don't know the limits of inputs that produce this issue, but here's one:

$ printf '%s\n' a b c d e f g h i j k >A.txt
$ printf '%s\n' a b c d e f f.5 g h i j k >B.txt
$ diff -u A.txt B.txt
--- A.txt
+++ B.txt
@@ -4,6 +4,7 @@
 d
 e
 f
+f.5
 g
 h
 i
$ diff -u A.txt B.txt | dunk
                          1 file changed
                       +1 ━━━━━━━━━━━━━ -0

▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ A.txt (1 additions, 0 removals) ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁
╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲ @@ -4,6 +4,7 @@  ╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲
   4 d                              4 d
   5 e                              5 e
   6 f                              6 f
╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲╲   7 g
   7 g                              8 h
   8 h                              9 i
   9 i                             10 j
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
                                               /// dunk 0.5.0b0

The line with f.5 is missing from the final output.

Python 3.13.7