Use fetch for downloading bottles.

Fixes Homebrew/homebrew#10958.

Library/Homebrew/cmd/fetch.rb

@@ -29,21 +29,23 @@ module Homebrew extend self
       the_tarball, _ = f.fetch
       next unless the_tarball.kind_of? Pathname
 
-      previous_md5 = f.instance_variable_get(:@md5).to_s.downcase
+      bottle = install_bottle? f
+
+      previous_md5 = f.instance_variable_get(:@md5).to_s.downcase unless bottle
       previous_sha1 = f.instance_variable_get(:@sha1).to_s.downcase
-      previous_sha2 = f.instance_variable_get(:@sha256).to_s.downcase
+      previous_sha2 = f.instance_variable_get(:@sha256).to_s.downcase unless bottle
 
-      puts "MD5:  #{the_tarball.md5}"
+      puts "MD5:  #{the_tarball.md5}" unless bottle
       puts "SHA1: #{the_tarball.sha1}"
-      puts "SHA256: #{the_tarball.sha2}"
+      puts "SHA256: #{the_tarball.sha2}" unless bottle
 
-      unless previous_md5.nil? or previous_md5.empty? or the_tarball.md5 == previous_md5
+      unless previous_md5.nil? or previous_md5.empty? or the_tarball.md5 == previous_md5 or bottle
         opoo "Formula reports different MD5: #{previous_md5}"
       end
       unless previous_sha1.nil? or previous_sha1.empty? or the_tarball.sha1 == previous_sha1
         opoo "Formula reports different SHA1: #{previous_sha1}"
       end
-      unless previous_sha2.nil? or previous_sha2.empty? or the_tarball.sha2 == previous_sha2
+      unless previous_sha2.nil? or previous_sha2.empty? or the_tarball.sha2 == previous_sha2 or bottle
         opoo "Formula reports different SHA256: #{previous_sha2}"
       end
     end

Library/Homebrew/formula.rb

@@ -443,10 +443,14 @@ public
 
   # For brew-fetch and others.
   def fetch
-    downloader = @downloader
-    # Don't attempt mirrors if this install is not pointed at a "stable" URL.
-    # This can happen when options like `--HEAD` are invoked.
-    mirror_list =  @spec_to_use == @standard ? mirrors : []
+    if install_bottle? self
+      downloader = CurlBottleDownloadStrategy.new bottle_url, name, version, nil
+    else
+      downloader = @downloader
+      # Don't attempt mirrors if this install is not pointed at a "stable" URL.
+      # This can happen when options like `--HEAD` are invoked.
+      mirror_list =  @spec_to_use == @standard ? mirrors : []
+    end
 
     # Ensure the cache exists
     HOMEBREW_CACHE.mkpath

Library/Homebrew/formula_installer.rb

@@ -253,10 +253,8 @@ class FormulaInstaller
   end
 
   def pour
-    HOMEBREW_CACHE.mkpath
-    downloader = CurlBottleDownloadStrategy.new f.bottle_url, f.name, f.version, nil
-    downloader.fetch
-    f.verify_download_integrity downloader.tarball_path, f.bottle_sha1, "SHA1"
+    fetched, downloader = f.fetch
+    f.verify_download_integrity fetched, f.bottle_sha1, "SHA1"
     HOMEBREW_CELLAR.cd do
       downloader.stage
     end