reader: make Escape during history search restore commandline again

Commit 3b30d92b6 (Commit transient edit when closing pager, 2022-08-31)
inadvertently introduced two regressions to history search:

1. It made Escape keeps the selected history entry,
   instead of restoring the commandline before history search.
2. It made history search commands add undo entries.

Fix both of this issues.

CHANGELOG.rst

@@ -24,6 +24,7 @@ Interactive improvements
 - Using ``fish_vi_key_bindings`` in combination with fish's ``--no-config`` mode works without locking up the shell (:issue:`9443`).
 - The history pager now uses more screen space, usually half the screen (:issue:`9458`)
 - Variables that were set while the locale was C (i.e. ASCII) will now properly be encoded if the locale is switched (:issue:`2613`, :issue:`9473`).
+- Escape during history search restores the original commandline again (regressed in 3.6.0).
 
 New or improved bindings
 ^^^^^^^^^^^^^^^^^^^^^^^^

src/reader.cpp

@@ -4482,7 +4482,8 @@ maybe_t<wcstring> reader_data_t::readline(int nchars_or_0) {
 
             // Clear the pager if necessary.
             bool focused_on_search_field = (active_edit_line() == &pager.search_field_line);
-            if (command_ends_paging(readline_cmd, focused_on_search_field)) {
+            if (!history_search.active() &&
+                command_ends_paging(readline_cmd, focused_on_search_field)) {
                 clear_pager();
             }
 

tests/checks/tmux-history-search.fish

@@ -3,6 +3,9 @@
 # disable on github actions because it's flakey
 #REQUIRES: test -z "$CI"
 
+set -g isolated_tmux_fish_extra_args -C '
+    set -g fish_autosuggestion_enabled 0
+'
 isolated-tmux-start
 
 isolated-tmux send-keys 'true needle' Enter
@@ -15,3 +18,12 @@ isolated-tmux send-keys C-p C-a M-f M-f M-f M-.
 # CHECK: prompt 2> true hay needle hay
 tmux-sleep
 isolated-tmux capture-pane -p
+
+isolated-tmux send-keys C-e C-u true Up Up Escape
+tmux-sleep
+isolated-tmux capture-pane -p | grep 'prompt 2'
+# CHECK: prompt 2> true
+isolated-tmux send-keys C-z _
+tmux-sleep
+isolated-tmux capture-pane -p | grep 'prompt 2'
+# CHECK: prompt 2> _