Add helper functions for --cache and fetch explicitly.

Library/Homebrew/cmd/--cache.rb

@@ -6,6 +6,8 @@ require "cask/cmd"
 require "cask/cask_loader"
 
 module Homebrew
+  extend Fetch
+
   module_function
 
   def __cache_args
@@ -58,7 +60,7 @@ module Homebrew
 
   def print_formula_cache(name)
     formula = Formulary.factory name
-    if Fetch.fetch_bottle?(formula)
+    if fetch_bottle?(formula)
       puts formula.bottle.cached_download
     else
       puts formula.cached_download

Library/Homebrew/cmd/fetch.rb

@@ -5,6 +5,8 @@ require "fetch"
 require "cli/parser"
 
 module Homebrew
+  extend Fetch
+
   module_function
 
   def fetch_args
@@ -62,7 +64,7 @@ module Homebrew
       f.print_tap_action verb: "Fetching"
 
       fetched_bottle = false
-      if Fetch.fetch_bottle?(f)
+      if fetch_bottle?(f)
         begin
           fetch_formula(f.bottle)
         rescue Interrupt

Library/Homebrew/fetch.rb

@@ -2,12 +2,10 @@
 
 module Homebrew
   module Fetch
-    module_function
-
     def fetch_bottle?(f)
-      return true if Homebrew.args.force_bottle? && f.bottle
+      return true if args.force_bottle? && f.bottle
       return false unless f.bottle && f.pour_bottle?
-      return false if Homebrew.args.build_formula_from_source?(f)
+      return false if args.build_formula_from_source?(f)
       return false unless f.bottle.compatible_cellar?
 
       true