--repository: use CLI::Parser.

Library/Homebrew/cmd/--repository.rb

@@ -1,13 +1,23 @@
-#:  * `--repository`:
-#:    Display where Homebrew's `.git` directory is located.
-#:
-#:  * `--repository` <user>`/`<repo>:
-#:    Display where tap <user>`/`<repo>'s directory is located.
+require "cli_parser"
 
 module Homebrew
   module_function
 
+  def __repository_args
+    Homebrew::CLI::Parser.new do
+      usage_banner <<~EOS
+        `--repository` [<formula>]
+
+        Display where Homebrew's `.git` directory is located.
+
+        If <user>`/`<repo> are provided, display where tap <user>`/`<repo>'s directory is located.
+      EOS
+    end
+  end
+
   def __repository
+    __repository_args.parse
+
     if ARGV.named.empty?
       puts HOMEBREW_REPOSITORY
     else