Disallow running `brew cask` as `root`.

Library/Homebrew/brew.sh

@@ -240,9 +240,6 @@ fi
 check-run-command-as-root() {
   [[ "$(id -u)" = 0 ]] || return
 
-  # Homebrew Cask may need `sudo` for system-wide installation.
-  [[ "$HOMEBREW_COMMAND" = "cask" ]] && return
-
   # Homebrew Services may need `sudo` for system-wide daemons.
   [[ "$HOMEBREW_COMMAND" = "services" ]] && return
 

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

@@ -31,7 +31,6 @@ module Hbc
         ohai "Contents of $PATH Environment Variable:", render_env_var("PATH")
         ohai "Contents of $SHELL Environment Variable:", render_env_var("SHELL")
         ohai "Contents of Locale Environment Variables:", render_with_none(locale_variables)
-        ohai "Running As Privileged User:", render_with_none_as_error(privileged_uid)
       end
 
       def self.alt_taps
@@ -107,12 +106,6 @@ module Hbc
         ENV.keys.grep(/^(?:LC_\S+|LANG|LANGUAGE)\Z/).collect { |v| %Q(#{v}="#{ENV[v]}") }.sort.join("\n")
       end
 
-      def self.privileged_uid
-        Process.euid.zero? ? "Yes #{error_string "warning: not recommended"}" : "No"
-      rescue StandardError
-        notfound_string
-      end
-
       def self.none_string
         "<NONE>"
       end