Deprecate _fetch without timeout option.

Library/Homebrew/compat/early.rb

@@ -0,0 +1,4 @@
+# typed: strict
+# frozen_string_literal: true
+
+require_relative "early/download_strategy"

Library/Homebrew/compat/late.rb

@@ -1,4 +1,4 @@
 # typed: strict
 # frozen_string_literal: true
 
-require "compat/download_strategy"
+require_relative "late/download_strategy"

Library/Homebrew/compat/late/download_strategy.rb

@@ -0,0 +1,20 @@
+# typed: false
+# frozen_string_literal: true
+
+class CurlDownloadStrategy
+  module Compat
+    def _fetch(*args, **options)
+      unless options.key?(:timeout)
+        odeprecated "#{self.class}#_fetch"
+        options[:timeout] = nil
+      end
+      super(*args, **options)
+    end
+  end
+
+  prepend Compat
+end
+
+class CurlPostDownloadStrategy
+  prepend Compat
+end

Library/Homebrew/global.rb

@@ -75,7 +75,7 @@ HOMEBREW_BOTTLES_EXTNAME_REGEX = /\.([a-z0-9_]+)\.bottle\.(?:(\d+)\.)?tar\.gz$/.
 require "utils/sorbet"
 
 require "env_config"
-require "compat" unless Homebrew::EnvConfig.no_compat?
+require "compat/early" unless Homebrew::EnvConfig.no_compat?
 require "os"
 require "messages"
 
@@ -154,3 +154,5 @@ require "tap_constants"
 
 # Enables `patchelf.rb` write support.
 HOMEBREW_PATCHELF_RB_WRITE = ENV["HOMEBREW_NO_PATCHELF_RB_WRITE"].blank?.freeze
+
+require "compat/late" unless Homebrew::EnvConfig.no_compat?

Library/Homebrew/system_command.rb

@@ -220,6 +220,7 @@ class SystemCommand
     loop do
       readable_sources, = IO.select(sources_remaining, [], [], end_time&.remaining!)
       raise Timeout::Error if readable_sources.nil?
+
       readable_sources = T.must(readable_sources)
 
       break if readable_sources.empty?