Add support for ref: in gem.deps.rb.lock for git

This support was omitted.  The ref: doesn't seem to do anything useful
in bundler (its only fetched for an equality comparison) so it is
ignored here.

Bug rubygems#822

History.txt

@@ -39,6 +39,8 @@ Bug fixes:
   now.  Bug #821 by johnny5-.
 * Gem dependency API supports lockfiles without explicit sources.  Bug #820 by
   johnny5-.
+* Gem dependency API supports lockfiles with git sources using ref.  Bug #822
+  by johnny5-.
 * SSL configuration entries in ~/.gemrc are properly round-tripped.  Bug #837
   by Noah Luck Easterly.
 * The environment command now shows the system configuration directory where

lib/rubygems/request_set/lockfile.rb

@@ -341,6 +341,13 @@ def parse_GIT # :nodoc:
 
     skip :newline
 
+    if [:entry, 'ref'] == peek.first(2) then
+      get
+      get :text
+
+      skip :newline
+    end
+
     get :entry, 'specs'
 
     skip :newline

test/rubygems/test_gem_request_set_lockfile.rb

@@ -200,6 +200,49 @@ def test_parse_GIT
     assert_equal %w[a-2], git_set.specs.values.map { |s| s.full_name }
 
     assert_equal [dep('b', '>= 3')], git_set.specs.values.first.dependencies
+
+    expected = {
+      'a' => %w[git://example/a.git master],
+    }
+
+    assert_equal expected, git_set.repositories
+  end
+
+  def test_parse_GIT_ref
+    write_lockfile <<-LOCKFILE
+GIT
+  remote: git://example/a.git
+  revision: 1234abc
+  ref: 1234abc
+  specs:
+    a (2)
+      b (>= 3)
+
+DEPENDENCIES
+  a!
+    LOCKFILE
+
+    @lockfile.parse
+
+    assert_equal [dep('a', '= 2')], @set.dependencies
+
+    lockfile_set = @set.sets.find do |set|
+      Gem::Resolver::LockSet === set
+    end
+
+    refute lockfile_set, 'fount a LockSet'
+
+    git_set = @set.sets.find do |set|
+      Gem::Resolver::GitSet === set
+    end
+
+    assert git_set, 'could not find a GitSet'
+
+    expected = {
+      'a' => %w[git://example/a.git 1234abc],
+    }
+
+    assert_equal expected, git_set.repositories
   end
 
   def test_parse_PATH