Let Cask handle the -h flag

Library/Homebrew/brew.rb

@@ -80,7 +80,13 @@ begin
   # - no arguments are passed
   if empty_argv || help_flag
     require "cmd/help"
+    if cmd == "cask"
+      # Let Cask handle the help command
+      Homebrew.send cmd.to_s.tr("-", "_").downcase
+      exit 0
+    else
       Homebrew.help cmd, empty_argv: empty_argv
+    end
     # `Homebrew.help` never returns, except for external/unknown commands.
   end
 

Library/Homebrew/cask/lib/hbc/cli.rb

@@ -154,7 +154,7 @@ module Hbc
     def run
       command_name, *args = detect_command_and_arguments(*@args)
       command = if help?
-        args.unshift(command_name)
+        args.unshift(command_name) if !command_name.nil?
         "help"
       else
         self.class.lookup_command(command_name)
@@ -230,8 +230,7 @@ module Hbc
 
         return if @command == "help" && @args.empty?
 
-        unknown_command = (@command == "help") ? @args.first : @command
-        raise ArgumentError, "Unknown command: #{unknown_command}"
+        raise ArgumentError, "help does not take arguments"
       end
 
       def purpose