Add support for FZF_DEFAULT_OPTS_FILE (#319)

Don't set default fzf options if FZF_DEFAULT_OPTS_FILE is set. FZF_DEFAULT_OPTS_FILE was added to fzf in version 0.47.0

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Co-authored-by: Patrick Fong <patrickf3139@gmail.com>

README.md

@@ -112,9 +112,7 @@ Call `fzf_configure_bindings` in your `config.fish` in order to persist your cus
 
 ### Change fzf options for all commands
 
-fzf supports global default options via the [FZF_DEFAULT_OPTS](https://github.com/junegunn/fzf#environment-variables) environment variable.
-
-`fzf.fish` sets [a sane `FZF_DEFAULT_OPTS` whenever it executes fzf](functions/_fzf_wrapper.fish). If you export your own `FZF_DEFAULT_OPTS`, then yours will be used instead.
+fzf supports global default options via the [FZF_DEFAULT_OPTS and FZF_DEFAULT_OPTS_FILE](https://github.com/junegunn/fzf#environment-variables) environment variables. If neither are set, `fzf.fish` sets its own [default opts whenever it executes fzf](functions/_fzf_wrapper.fish).
 
 ### Change fzf options for a specific command
 

functions/_fzf_wrapper.fish

@@ -4,9 +4,10 @@ function _fzf_wrapper --description "Prepares some environment variables before
     # Use --function so that it doesn't clobber SHELL outside this function.
     set -f --export SHELL (command --search fish)
 
-    # If FZF_DEFAULT_OPTS is not set, then set some sane defaults.
+    # If neither FZF_DEFAULT_OPTS nor FZF_DEFAULT_OPTS_FILE are set, then set some sane defaults.
     # See https://github.com/junegunn/fzf#environment-variables
-    if not set --query FZF_DEFAULT_OPTS
+    set --query FZF_DEFAULT_OPTS FZF_DEFAULT_OPTS_FILE
+    if test $status -eq 2
         # cycle allows jumping between the first and last results, making scrolling faster
         # layout=reverse lists results top to bottom, mimicking the familiar layouts of git log, history, and env
         # border shows where the fzf window begins and ends