Fix off-by-one pager height error on empty lines

Commit 7db9553 (Fix regression causing off-by-one pager height on
truncated autosuggestion) adds line to pager if cursor located at
the start of line and previous line is softwrapped, even if line was
softwrapped normally and not by autosuggestion, giving pager too much space.

Fix that.

Part of #11911

src/screen.rs

@@ -29,7 +29,7 @@
 use crate::fallback::fish_wcwidth;
 use crate::flog::FLOGF;
 use crate::global_safety::RelaxedAtomicBool;
-use crate::highlight::{HighlightColorResolver, HighlightSpec};
+use crate::highlight::{HighlightColorResolver, HighlightRole, HighlightSpec};
 use crate::terminal::TerminalCommand::{
     self, ClearToEndOfLine, ClearToEndOfScreen, CursorDown, CursorLeft, CursorMove, CursorRight,
     CursorUp, EnterDimMode, ExitAttributeMode, Osc133PromptStart, ScrollContentUp,
@@ -457,12 +457,13 @@ struct ScrolledCursor {
 
         let full_line_count = self.desired.cursor.y
             - if self.desired.cursor.x == 0
-                && self
-                    .desired
-                    .cursor
-                    .y
-                    .checked_sub(1)
-                    .is_some_and(|y| self.desired.line_datas[y].is_soft_wrapped)
+                && self.desired.cursor.y.checked_sub(1).is_some_and(|y| {
+                    self.desired.line_datas[y].is_soft_wrapped
+                        && self.desired.line_datas[y]
+                            .color_at(self.desired.line_datas[y].len() - 1)
+                            .foreground
+                            == HighlightRole::autosuggestion
+                })
             {
                 1
             } else {

tests/checks/tmux-pager.fish

@@ -9,6 +9,7 @@ set -g isolated_tmux_fish_extra_args -C '
 
 isolated-tmux-start
 
+# Check that completions don't break from truncated autosuggestion
 isolated-tmux send-keys : Space Tab Tab
 tmux-sleep
 isolated-tmux capture-pane -p
@@ -22,3 +23,19 @@ isolated-tmux capture-pane -p
 # CHECK: 7    141  275  409  543  677
 # CHECK: 8    142  276  410  544  678
 # CHECK: rows 1 to 8 of 134
+
+# Check that completions don't break than called on empty line
+isolated-tmux send-keys C-u 'set fish_autosuggestion_enabled 0; function fish_prompt; string repeat (math $COLUMNS - 2) 0; end' Enter
+isolated-tmux send-keys C-l : Space Tab Tab
+tmux-sleep
+isolated-tmux capture-pane -p
+# CHECK: 000000000000000000000000000000000000000000000000000000000000000000000000000000:
+# CHECK:
+# CHECK: 1    135  269  403  537  671
+# CHECK: 2    136  270  404  538  672
+# CHECK: 3    137  271  405  539  673
+# CHECK: 4    138  272  406  540  674
+# CHECK: 5    139  273  407  541  675
+# CHECK: 6    140  274  408  542  676
+# CHECK: 7    141  275  409  543  677
+# CHECK: rows 1 to 7 of 134