Pass `args` in `postinstall` instead of using global `args`.

Library/Homebrew/postinstall.rb

@@ -10,13 +10,13 @@ require "cli/parser"
 require "cmd/postinstall"
 
 begin
-  Homebrew.postinstall_args.parse
+  args = Homebrew.postinstall_args.parse
   error_pipe = UNIXSocket.open(ENV["HOMEBREW_ERROR_PIPE"], &:recv_io)
   error_pipe.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
 
   trap("INT", old_trap)
 
-  formula = Homebrew.args.resolved_formulae.first
+  formula = args.resolved_formulae.first
   formula.extend(Debrew::Formula) if Homebrew.args.debug?
   formula.run_post_install
 rescue Exception => e # rubocop:disable Lint/RescueException