[fish] Merge history before searching (#3852)

Co-authored-by: Junegunn Choi <junegunn.c@gmail.com>

shell/key-bindings.fish

@@ -62,6 +62,11 @@ function fzf_key_bindings
       set -l FISH_MAJOR (echo $version | cut -f1 -d.)
       set -l FISH_MINOR (echo $version | cut -f2 -d.)
 
+      # merge history from other sessions before searching
+      if test -z "$fish_private_mode"
+        builtin history merge
+      end
+
       # history's -z flag is needed for multi-line support.
       # history's -z flag was added in fish 2.4.0, so don't use it for versions
       # before 2.4.0.

test/test_go.rb

@@ -66,7 +66,7 @@ class Shell
     end
 
     def fish
-      "unset #{UNSETS.join(' ')}; FZF_DEFAULT_OPTS=\"--no-scrollbar --pointer '>' --marker '>'\" fish_history= fish"
+      "unset #{UNSETS.join(' ')}; rm -f ~/.local/share/fish/fzf_test_history; FZF_DEFAULT_OPTS=\"--no-scrollbar --pointer '>' --marker '>'\" fish_history=fzf_test fish"
     end
   end
 end