[fish] Refactor fzf-history-widget

- Remove check/set of FZF_TMUX_HEIGHT variable. It is already done by
  __fzf_defaults.
- Remove unnecessary begin/end block.
- Pass all fzf options (except query) through FZF_DEFAULT_OPTS variable.

shell/key-bindings.fish

@@ -52,15 +52,16 @@ function fzf_key_bindings
   end
 
   function fzf-history-widget -d "Show command history"
-    test -n "$FZF_TMUX_HEIGHT"; or set FZF_TMUX_HEIGHT 40%
+    set -l fzf_query (commandline | string escape)
-    begin
-      # merge history from other sessions before searching
-      test -z "$fish_private_mode"; and builtin history merge
 
-      set -lx FZF_DEFAULT_OPTS (__fzf_defaults "" "-n2..,.. --scheme=history --bind=ctrl-r:toggle-sort --wrap-sign '"\t"↳ ' --highlight-line +m $FZF_CTRL_R_OPTS")
+    set -lx FZF_DEFAULT_OPTS (__fzf_defaults '' \
-      set -lx FZF_DEFAULT_OPTS_FILE ''
+      '--nth=2..,.. --scheme=history --bind=ctrl-r:toggle-sort --wrap-sign="\t↳ "' \
+      "--highlight-line --no-multi $FZF_CTRL_R_OPTS --read0 --print0" \
+      "--bind='enter:become:string replace -a -- \n\t \n {2..} | string collect'" \
+      '--with-shell='(status fish-path)\\ -c)
+
+    set -lx FZF_DEFAULT_OPTS_FILE
     set -lx FZF_DEFAULT_COMMAND
-      set -a -- FZF_DEFAULT_OPTS --with-shell=(status fish-path)\\ -c
 
     if type -q perl
       set -a FZF_DEFAULT_OPTS '--tac'
@@ -72,9 +73,13 @@ function fzf_key_bindings
         'string join0 -- $i\t(string replace -a -- \n \n\t $h[$i] | string collect);' \
         'end'
     end
-      set -l result (eval $FZF_DEFAULT_COMMAND \| (__fzfcmd) --read0 --print0 -q (commandline | string escape) "--bind=enter:become:'string replace -a -- \n\t \n {2..} | string collect'")
+
+    # Merge history from other sessions before searching
+    test -z "$fish_private_mode"; and builtin history merge
+
+    set -l result (eval $FZF_DEFAULT_COMMAND \| (__fzfcmd) --query=$fzf_query)
     and commandline -- $result
-    end
+
     commandline -f repaint
   end