Fix diff output when a diff ends with a mode change

Output can be generated directly via Painter::write, or Painter::output_buffer.
The latter must be emit()'ed before the former method can be used again,
otherwise the order is incorrect.

Tests added. Fixes #1504

1 files changed, 1 insertions, 0 deletions

diff --git a/src/handlers/diff_header_diff.rs b/src/handlers/diff_header_diff.rs
index e88f89d..70aca72 100644
--- a/src/handlers/diff_header_diff.rs
+++ b/src/handlers/diff_header_diff.rs
@@ -13,6 +13,7 @@ impl StateMachine<'_> {
             return Ok(false);
         }
         self.painter.paint_buffered_minus_and_plus_lines();
+        self.painter.emit()?;
         self.state =
             if self.line.starts_with("diff --cc ") || self.line.starts_with("diff --combined ") {
                 // We will determine the number of parents when we see the hunk header.