search: return results while parsing

Instead of returning a full list of results after parsing, yield and
print each result as it's found for a snappier user experience.

Closes Homebrew/homebrew#9576.

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>

Library/Homebrew/cmd/search.rb

@@ -29,10 +29,8 @@ module Homebrew extend self
       end
 
       if search_results.empty? and not blacklisted? query
-        pulls = GitHub.find_pull_requests rx
-        unless pulls.empty?
-          puts "Open pull requests matching \"#{query}\":", *pulls.map { |p| "    #{p}" }
-        end
+        puts "No formula found for \"#{query}\". Searching open pull requests..."
+        GitHub.find_pull_requests(rx) { |pull| puts pull }
       end
     end
   end

Library/Homebrew/utils.rb

@@ -432,17 +432,15 @@ module GitHub extend self
     require 'open-uri'
     require 'vendor/multi_json'
 
-    pulls = []
     query = rx.source.delete '.*'
     uri = URI.parse("http://github.com/api/v2/json/issues/search/mxcl/homebrew/open/#{query}")
 
     open uri do |f|
       MultiJson.decode(f.read)["issues"].each do |pull|
-        pulls << pull['pull_request_url'] if rx.match pull['title'] and pull["pull_request_url"]
+        yield pull['pull_request_url'] if rx.match pull['title'] and pull["pull_request_url"]
       end
     end
-    pulls
   rescue
-    []
+    nil
   end
 end