Fix empty soft-wrapped line not being removed before execution

Commit 7acc2b7 added an empty line to our screen representation if we are
wrapped. This regressed the fix for #6826.  In the attached test case, there is
a spurious empty line after the first one.  Adjust the fix to remove it again.

Patch-by: kerty <g.kabakov@inbox.ru>
https://github.com/fish-shell/fish-shell/pull/11153#issuecomment-2800087389

src/screen.rs

@@ -756,11 +756,11 @@ pub fn save_status(&mut self) {
     /// Return whether we believe the cursor is wrapped onto the last line, and that line is
     /// otherwise empty. This includes both soft and hard wrapping.
     pub fn cursor_is_wrapped_to_own_line(&self) -> bool {
-        // Note == comparison against the line count is correct: we do not create a line just for the
-        // cursor. If there is a line containing the cursor, then it means that line has contents and we
-        // should return false.
         // Don't consider dumb terminals to have wrapping for the purposes of this function.
-        self.actual.cursor.x == 0 && self.actual.cursor.y == self.actual.line_count() && !is_dumb()
+        self.actual.cursor.x == 0
+            && self.actual.cursor.y != 0
+            && self.actual.cursor.y + 1 == self.actual.line_count()
+            && !is_dumb()
     }
 
     /// Appends a character to the end of the line that the output cursor is on. This function

tests/checks/tmux-wrapping.fish

@@ -0,0 +1,17 @@
+#RUN: %fish %s
+#REQUIRES: command -v tmux
+
+set -g isolated_tmux_fish_extra_args -C '
+    function fish_prompt; echo \'$ \'; end
+    bind ctrl-g "commandline -i \'echo \'(printf %0(math \$COLUMNS - (string length \'\$ echo \'))d 0)"
+'
+isolated-tmux-start
+
+isolated-tmux send-keys C-g Enter
+tmux-sleep
+isolated-tmux capture-pane -p | awk 'NR <= 4 {print NR ":" $0}'
+
+# CHECK: 1:$ echo 0000000000000000000000000000000000000000000000000000000000000000000000000
+# CHECK: 2:0000000000000000000000000000000000000000000000000000000000000000000000000
+# CHECK: 3:$
+# CHECK: 4: