Pass a User-Agent when fetching data from the GitHub API

See <http://developer.github.com/v3/#user-agent-required>.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Contributions/cmd/brew-ls-taps.rb

@@ -1,8 +1,7 @@
-require 'open-uri'
 require 'vendor/multi_json'
 
 begin
-  open "https://api.github.com/legacy/repos/search/homebrew" do |f|
+  GitHub.open "https://api.github.com/legacy/repos/search/homebrew" do |f|
     MultiJson.decode(f.read)["repositories"].each do |repo|
       if repo['name'] =~ /^homebrew-(\S+)$/
         puts tap = if repo['username'] == "Homebrew"

Library/Homebrew/cmd/search.rb

@@ -1,5 +1,6 @@
 require "formula"
 require "blacklist"
+require "utils"
 
 module Homebrew extend self
   def search
@@ -59,12 +60,10 @@ module Homebrew extend self
 
   def search_tap user, repo, rx
     return [] if (HOMEBREW_LIBRARY/"Taps/#{user.downcase}-#{repo.downcase}").directory?
-
-    require 'open-uri'
     require 'vendor/multi_json'
 
     results = []
-    open "https://api.github.com/repos/#{user}/homebrew-#{repo}/git/trees/HEAD?recursive=1" do |f|
+    GitHub.open "https://api.github.com/repos/#{user}/homebrew-#{repo}/git/trees/HEAD?recursive=1" do |f|
       user.downcase! if user == "Homebrew" # special handling for the Homebrew organization
       MultiJson.decode(f.read)["tree"].map{ |hash| hash['path'] }.compact.each do |file|
         name = File.basename(file, '.rb')

Library/Homebrew/utils.rb

@@ -257,6 +257,11 @@ def nostdout
 end
 
 module GitHub extend self
+  def open url, headers={}, &block
+    require 'open-uri'
+    Kernel.open(url, headers.merge('User-Agent' => HOMEBREW_USER_AGENT), &block)
+  end
+  
   def issues_for_formula name
     # bit basic as depends on the issue at github having the exact name of the
     # formula in it. Which for stuff like objective-caml is unlikely. So we
@@ -264,7 +269,6 @@ module GitHub extend self
 
     name = f.name if Formula === name
 
-    require 'open-uri'
     require 'vendor/multi_json'
 
     issues = []
@@ -284,13 +288,12 @@ module GitHub extend self
   end
 
   def find_pull_requests rx
-    require 'open-uri'
     require 'vendor/multi_json'
 
     query = rx.source.delete('.*').gsub('\\', '')
     uri = URI.parse("https://api.github.com/legacy/issues/search/mxcl/homebrew/open/#{query}")
 
-    open uri do |f|
+    GitHub.open uri do |f|
       MultiJson.decode(f.read)['issues'].each do |pull|
         yield pull['pull_request_url'] if rx.match pull['title'] and pull['pull_request_url']
       end