Shell out only once to list git remotes and their URLs

Each hub invocation would previously shell out twice to `git remote`:
1. Once to get the list of available remote names
2. A second time to obtain remote URLs with `remote -v`

With the new approach, we get the list of available remotes and collect
their URLs in the same pass. This is part of an effort to reduce the
number of shelling out to git if not absolutely necessary.

lib/hub/context.rb

@@ -194,12 +194,17 @@ def master_branch
 
       def remotes
         @remotes ||= begin
-          # TODO: is there a plumbing command to get a list of remotes?
-          list = git_command('remote').to_s.split("\n")
-          list = ORIGIN_NAMES.inject([]) { |sorted, name|
-            sorted << list.delete(name)
-          }.compact.concat(list)
-          list.map { |name| Remote.new self, name }
+          names = []
+          url_memo = Hash.new {|h,k| names << k; h[k]=[] }
+          git_command('remote -v').to_s.split("\n").map do |line|
+            next if line !~ /^(.+?)\t(.+) \(/
+            name, url = $1, $2
+            url_memo[name] << url
+          end
+          ((ORIGIN_NAMES + names) & names).map do |name|
+            urls = url_memo[name].uniq
+            Remote.new(self, name, urls)
+          end
         end
       end
 
@@ -376,15 +381,15 @@ def remote_name
       end
     end
 
-    class Remote < Struct.new(:local_repo, :name)
+    class Remote < Struct.new(:local_repo, :name, :raw_urls)
       alias to_s name
 
       def ==(other)
         other.respond_to?(:to_str) ? name == other.to_str : super
       end
 
       def project
-        urls.each_value { |url|
+        urls.each { |url|
           if valid = GithubProject.from_url(url, local_repo)
             return valid
           end
@@ -393,21 +398,21 @@ def project
       end
 
       def urls
-        return @urls if defined? @urls
-        @urls = {}
-        local_repo.git_command('remote -v').to_s.split("\n").map do |line|
-          next if line !~ /^(.+?)\t(.+) \((.+)\)$/
-          remote, uri, type = $1, $2, $3
-          next if remote != self.name
-          if uri =~ %r{^[\w-]+://} or uri =~ %r{^([^/]+?):}
-            uri = "ssh://#{$1}/#{$'}" if $1
+        @urls ||= raw_urls.map do |url|
+          with_normalized_url(url) do |normalized|
             begin
-              @urls[type] = uri_parse(uri)
+              uri_parse(normalized)
             rescue URI::InvalidURIError
             end
           end
         end
-        @urls
+      end
+
+      def with_normalized_url(url)
+        if url =~ %r{^[\w-]+://} || url =~ %r{^([^/]+?):}
+          url = "ssh://#{$1}/#{$'}" if $1
+          yield url
+        end
       end
 
       def uri_parse uri

test/hub_test.rb

@@ -99,7 +99,6 @@ def setup
     end
 
     @git_reader.stub! \
-      'remote' => "mislav\norigin",
       'remote -v' => "origin\tgit://github.com/defunkt/hub.git (fetch)\nmislav\tgit://github.com/mislav/hub.git (fetch)",
       'rev-parse --symbolic-full-name master@{upstream}' => 'refs/remotes/origin/master',
       'config --get --bool hub.http-clone' => 'false',
@@ -520,7 +519,7 @@ def stub_remotes_group(name, value)
     end
 
     def stub_no_remotes
-      stub_command_output 'remote', nil
+      stub_command_output 'remote -v', nil
     end
 
     def stub_no_git_repo