fish_update_completions: use status get-file instead of temp files

This helps the next commit.

share/functions/fish_update_completions.fish

@@ -5,25 +5,19 @@ function fish_update_completions --description "Update man-page based completion
         return 1
     end
 
-    function __fish_update_completions -V python
-        set -l user_args $argv[..-2]
-        set -l tools $argv[-1]
-        set -l update_args \
-            # Don't write .pyc files.
-            -B \
-            $tools/create_manpage_completions.py \
-            # Use the manpath
-            --manpath \
-            # Clean up old completions
-            --cleanup-in $__fish_user_data_dir/generated_completions \
-            --cleanup-in $__fish_cache_dir/generated_completions \
-            # Display progress
-            --progress \
-            $user_args
+    set -l update_args \
+        # Don't write .pyc files.
+        -B \
+        $tools/create_manpage_completions.py \
+        # Use the manpath
+        --manpath \
+        # Clean up old completions
+        --cleanup-in $__fish_user_data_dir/generated_completions \
+        --cleanup-in $__fish_cache_dir/generated_completions \
+        # Display progress
+        --progress \
+        $argv
+
+    __fish_data_with_file tools/create_manpage_completions.py cat |
         $python $update_args
-    end
-    __fish_data_with_directory tools \
-        'create_manpage_completions\.py' \
-        __fish_update_completions $argv
-    __fish_with_status functions --erase __fish_update_completions
 end