feat(__load_completion): pass backslashless command to fallback loads

So that things work also for commands preceded by a backslash.

Co-authored-by: Koichi Murase <myoga.murase@gmail.com>

Author: scop

bash_completion

@@ -2567,7 +2567,7 @@ __load_completion()
             # Do not warn with . or .. (especially the former is common)
             [[ $compfile == */.?(.) ]] ||
                 echo "bash_completion: $compfile: is a directory" >&2
-        elif [[ -e $compfile ]] && . "$compfile"; then
+        elif [[ -e $compfile ]] && . "$compfile" "$cmd"; then
             [[ $backslash ]] && $(complete -p "$cmd") "\\$cmd"
             return 0
         fi