Fix diff recalculation hang (#28377)

Fixes https://github.com/zed-industries/zed/issues/26039

Release Notes:

- Fixed an issue where diffs stopped updating closing and reopening them
after staging hunks.
- Fixed a bug where staging a hunk while the cursor was in a deleted
line would move the cursor erroneously.

---------

Co-authored-by: Cole Miller <m@cole-miller.net>
Co-authored-by: João Marcos <marcospb19@hotmail.com>

crates/git_ui/src/commit_view.rs

@@ -356,7 +356,7 @@ async fn build_buffer_diff(
 
     cx.new(|cx| {
         let mut diff = BufferDiff::new(&buffer.text, cx);
-        diff.set_snapshot(diff_snapshot, &buffer.text, None, cx);
+        diff.set_snapshot(diff_snapshot, &buffer.text, cx);
         diff
     })
 }

crates/git_ui/src/project_diff.rs

@@ -1501,7 +1501,6 @@ mod tests {
             .unindent(),
         );
 
-        eprintln!(">>>>>>>> git restore");
         let prev_buffer_hunks =
             cx.update_window_entity(&buffer_editor, |buffer_editor, window, cx| {
                 let snapshot = buffer_editor.snapshot(window, cx);
@@ -1525,7 +1524,6 @@ mod tests {
             });
         assert_eq!(new_buffer_hunks.as_slice(), &[]);
 
-        eprintln!(">>>>>>>> modify");
         cx.update_window_entity(&buffer_editor, |buffer_editor, window, cx| {
             buffer_editor.set_text("different\n", window, cx);
             buffer_editor.save(false, project.clone(), window, cx)
@@ -1554,8 +1552,8 @@ mod tests {
             cx,
             &"
                 - original
-                + ˇdifferent
-            "
+                + different
+                  ˇ"
             .unindent(),
         );
     }