[fish] Fix ctrl-r regression in versions <2.4 (#972)

Close #966

shell/key-bindings.fish

@@ -39,8 +39,20 @@ function fzf_key_bindings
     set -q FZF_TMUX_HEIGHT; or set FZF_TMUX_HEIGHT 40%
     begin
       set -lx FZF_DEFAULT_OPTS "--height $FZF_TMUX_HEIGHT $FZF_DEFAULT_OPTS --tiebreak=index --bind=ctrl-r:toggle-sort $FZF_CTRL_R_OPTS +m"
-      history -z | eval (__fzfcmd) --read0 -q '(commandline)' | perl -pe 'chomp if eof' | read -lz result
-      and commandline -- $result
+
+      set -l FISH_MAJOR (echo $FISH_VERSION | cut -f1 -d.)
+      set -l FISH_MINOR (echo $FISH_VERSION | cut -f2 -d.)
+
+      # history's -z flag is needed for multi-line support.
+      # history's -z flag was added in fish 2.4.0, so don't use it for versions
+      # before 2.4.0.
+      if [ "$FISH_MAJOR" -gt 2 -o \( "$FISH_MAJOR" -eq 2 -a "$FISH_MINOR" -ge 4 \) ];
+        history -z | eval (__fzfcmd) --read0 -q '(commandline)' | perl -pe 'chomp if eof' | read -lz result
+        and commandline -- $result
+      else
+        history | eval (__fzfcmd) -q '(commandline)' | read -l result
+        and commandline -- $result
+      end
     end
     commandline -f repaint
   end