Send repaint requests through the input queue again

Another consequence of a583fe723 ("commandline -f foo" to skip queue
and execute immediately, 2024-04-08) is that "commandline -f repaint"
will paint the prompt with the current value of $status which might be
set from a shell command in a the currently executing binding, instead of
waiting for the top-level status. This is wrong, at least historically. It
surfaces in bindings like alt-w which always paint a status value of [1]
when on single-lines commandlines.

Another regression is that a redundant repaint in a signal handler outputs
an extra prompt.

Fix both by making repaint commands go over the input queue again.  This way,
they are always run with a good commandline state.  There is no need to
repaint immediately because I don't think anyone has a data dependency on it
(we currently don't expose the prompt string), it's only for rendering.

src/reader.rs

@@ -903,6 +903,19 @@ pub fn reader_schedule_prompt_repaint() {
 
 pub fn reader_execute_readline_cmd(ch: CharEvent) {
     if let Some(data) = current_data() {
+        let CharEvent::Readline(readline_cmd_evt) = &ch else {
+            panic!()
+        };
+        if matches!(
+            readline_cmd_evt.cmd,
+            ReadlineCmd::ClearScreenAndRepaint
+                | ReadlineCmd::RepaintMode
+                | ReadlineCmd::Repaint
+                | ReadlineCmd::ForceRepaint
+        ) {
+            data.inputter.queue_char(ch);
+            return;
+        }
         if data.rls.is_none() {
             data.rls = Some(ReadlineLoopState::new());
         }

tests/checks/tmux-prompt.fish

@@ -2,19 +2,37 @@
 #REQUIRES: command -v tmux
 
 set -g isolated_tmux_fish_extra_args -C '
-    function fish_prompt; printf "prompt $status_generation> <$prompt_var> "; end
+    function fish_prompt
+        printf "prompt $status_generation> <status=$status> <$prompt_var> "
+        set prompt_var ''
+    end
     function on_prompt_var --on-variable prompt_var
         commandline -f repaint
     end
+    function token-info
+        __fish_echo echo "current token is <$(commandline -t)>"
+    end
+    bind ctrl-g token-info
 '
 
 isolated-tmux-start
 
 isolated-tmux capture-pane -p
-# CHECK: prompt 0> <>
+# CHECK: prompt 0> <status=0> <>
 
 set -q CI && set sleep sleep 10
 set -U prompt_var changed
 tmux-sleep
+isolated-tmux send-keys Enter
+# CHECK: prompt 0> <status=0> <changed>
+
+isolated-tmux send-keys echo Space 123
+tmux-sleep
+isolated-tmux send-keys C-g
+
+# CHECK: prompt 0> <status=0> <> echo 123
+# CHECK: current token is <123>
+# CHECK: prompt 0> <status=0> <> echo 123
+tmux-sleep
+
 isolated-tmux capture-pane -p
-# CHECK: prompt 0> <changed>

tests/checks/tmux-signal.fish

@@ -0,0 +1,18 @@
+#RUN: %fish %s
+#REQUIRES: command -v tmux
+
+isolated-tmux-start
+
+isolated-tmux send-keys '
+    function usr1_handler --on-signal SIGUSR1
+        echo Got SIGUSR1
+        # This repaint is not needed but make sure it is coalesced.
+        commandline -f repaint
+    end
+' Enter
+isolated-tmux send-keys C-l 'kill -SIGUSR1 $fish_pid' Enter
+tmux-sleep
+isolated-tmux capture-pane -p
+# CHECK: prompt 1> kill -SIGUSR1 $fish_pid
+# CHECK: Got SIGUSR1
+# CHECK: prompt 2>