Require more HTTP mirrors for old OS X versions.

This allows the bootstrap of `curl` and `git` on versions of Mac OS X
that cannot reliably download from HTTPS servers any longer. Once these
are both installed users are able to update Homebrew and download files
securely.

Also, as we're doing this, don't point 10.5 users to Tigerbrew as they
are already given caveats for using Homebrew itself.

Library/Homebrew/dev-cmd/audit.rb

@@ -202,12 +202,12 @@ class FormulaAuditor
     @specs = %w[stable devel head].map { |s| formula.send(s) }.compact
   end
 
-  def self.check_http_content(url, name, user_agents: [:default], check_content: false, strict: false)
+  def self.check_http_content(url, user_agents: [:default], check_content: false, strict: false, require_http: false)
     return unless url.start_with? "http"
 
     details = nil
     user_agent = nil
-    hash_needed = url.start_with?("http:") && name != "curl"
+    hash_needed = url.start_with?("http:") && !require_http
     user_agents.each do |ua|
       details = http_content_headers_and_checksum(url, hash_needed: hash_needed, user_agent: ua)
       user_agent = ua
@@ -576,7 +576,6 @@ class FormulaAuditor
 
     return unless DevelopmentTools.curl_handles_most_https_homepages?
     if http_content_problem = FormulaAuditor.check_http_content(homepage,
-                                               formula.name,
                                                user_agents: [:browser, :default],
                                                check_content: true,
                                                strict: @strict)
@@ -629,13 +628,14 @@ class FormulaAuditor
     end
 
     %w[Stable Devel HEAD].each do |name|
-      next unless spec = formula.send(name.downcase)
+      spec_name = name.downcase.to_sym
+      next unless spec = formula.send(spec_name)
 
-      ra = ResourceAuditor.new(spec, online: @online, strict: @strict).audit
+      ra = ResourceAuditor.new(spec, spec_name, online: @online, strict: @strict).audit
       problems.concat ra.problems.map { |problem| "#{name}: #{problem}" }
 
       spec.resources.each_value do |resource|
-        ra = ResourceAuditor.new(resource, online: @online, strict: @strict).audit
+        ra = ResourceAuditor.new(resource, spec_name, online: @online, strict: @strict).audit
         problems.concat ra.problems.map { |problem|
           "#{name} resource #{resource.name.inspect}: #{problem}"
         }
@@ -1086,10 +1086,10 @@ class FormulaAuditor
 end
 
 class ResourceAuditor
-  attr_reader :problems
-  attr_reader :version, :checksum, :using, :specs, :url, :mirrors, :name
+  attr_reader :name, :version, :checksum, :url, :mirrors, :using, :specs, :owner
+  attr_reader :spec_name, :problems
 
-  def initialize(resource, options = {})
+  def initialize(resource, spec_name, options = {})
     @name     = resource.name
     @version  = resource.version
     @checksum = resource.checksum
@@ -1097,9 +1097,11 @@ class ResourceAuditor
     @mirrors  = resource.mirrors
     @using    = resource.using
     @specs    = resource.specs
-    @online   = options[:online]
-    @strict   = options[:strict]
-    @problems = []
+    @owner    = resource.owner
+    @spec_name = spec_name
+    @online    = options[:online]
+    @strict    = options[:strict]
+    @problems  = []
   end
 
   def audit
@@ -1173,11 +1175,26 @@ class ResourceAuditor
     problem "Redundant :using value in URL"
   end
 
+  def self.curl_git_openssl_and_deps
+    @curl_git_openssl_and_deps ||= begin
+      formulae_names = ["curl", "git", "openssl"]
+      formulae_names += formulae_names.flat_map do |f|
+        Formula[f].recursive_dependencies.map(&:name)
+      end
+      formulae_names.uniq
+    rescue FormulaUnavailableError
+      []
+    end
+  end
+
   def audit_urls
     urls = [url] + mirrors
 
-    if name == "curl" && !urls.find { |u| u.start_with?("http://") } && url != Formula["curl"].head.url
-      problem "should always include at least one HTTP url"
+    require_http = ResourceAuditor.curl_git_openssl_and_deps.include?(owner.name)
+
+    if spec_name == :stable && require_http &&
+       !urls.find { |u| u.start_with?("http://") }
+      problem "should always include at least one HTTP mirror"
     end
 
     return unless @online
@@ -1189,7 +1206,7 @@ class ResourceAuditor
         # A `brew mirror`'ed URL is usually not yet reachable at the time of
         # pull request.
         next if url =~ %r{^https://dl.bintray.com/homebrew/mirror/}
-        if http_content_problem = FormulaAuditor.check_http_content(url, name)
+        if http_content_problem = FormulaAuditor.check_http_content(url, name, require_http: require_http)
           problem http_content_problem
         end
       elsif strategy <= GitDownloadStrategy

docs/Installation.md

@@ -47,7 +47,7 @@ PowerPC and Tiger branches from other users in the fork network. See
 [Interesting Taps and Forks](Interesting-Taps-and-Forks.md).
 
 <a name="2"><sup>2</sup></a> 10.10 or higher is recommended. 10.5–10.9 are
-supported on a best-effort basis. For 10.4 and 10.5, see
+supported on a best-effort basis. For 10.4 see
 [Tigerbrew](https://github.com/mistydemeo/tigerbrew).
 
 <a name="3"><sup>3</sup></a> Most formulae require a compiler. A handful