Index: test/test_gem_source_info_cache.rb
===================================================================
--- test/test_gem_source_info_cache.rb	(revision 1692)
+++ test/test_gem_source_info_cache.rb	(working copy)
@@ -271,6 +271,32 @@
     assert_equal [@a2.full_name], gems
   end

+  # Replicates above but verifies #add_specs works with no splatting
+  def test_read_user_cache_without_splat
+    FileUtils.chmod 0444, @sic.user_cache_file
+    FileUtils.chmod 0444, @sic.latest_user_cache_file
+
+    @si = Gem::SourceIndex.new
+    @si.add_specs([@a1, @a2])
+
+    @sice = Gem::SourceInfoCacheEntry.new @si, 0
+
+    @sic.set_cache_data({ @gem_repo => @sice })
+    @sic.update
+    @sic.write_cache
+    @sic.reset_cache_data
+
+    user_cache_data = @sic.cache_data.to_a.sort
+
+    assert_equal 1, user_cache_data.length
+    user_cache_data = user_cache_data.first
+
+    assert_equal @gem_repo, user_cache_data.first
+
+    gems = user_cache_data.last.source_index.map { |_,spec| spec.full_name }
+    assert_equal [@a2.full_name], gems
+  end
+
   def test_search
     si = Gem::SourceIndex.new
     si.add_spec @a1
@@ -411,6 +437,47 @@
     assert_equal [@a2.full_name], gems
   end

+  # Replicates _from_scratch but verifies #add_specs works with no splat
+  def test_write_cache_user_from_scratch_without_splat
+    FileUtils.rm_rf @sic.user_cache_file
+    FileUtils.rm_rf @sic.latest_user_cache_file
+
+    FileUtils.chmod 0444, @sic.system_cache_file
+    FileUtils.chmod 0444, @sic.latest_system_cache_file
+
+    @si = Gem::SourceIndex.new
+    @si.add_specs([@a1, @a2])
+
+    @sice = Gem::SourceInfoCacheEntry.new @si, 0
+
+    @sic.set_cache_data({ @gem_repo => @sice })
+    @sic.update
+
+    @sic.write_cache
+
+    assert File.exist?(@sic.user_cache_file), 'system_cache_file'
+    assert File.exist?(@sic.latest_user_cache_file),
+           'latest_system_cache_file'
+
+    user_cache_data = read_cache(@sic.user_cache_file).to_a.sort
+    assert_equal 1, user_cache_data.length, 'user_cache_data length'
+    user_cache_data = user_cache_data.first
+
+    assert_equal @gem_repo, user_cache_data.first
+
+    gems = user_cache_data.last.source_index.map { |_,spec| spec.full_name }
+    assert_equal [@a1.full_name, @a2.full_name], gems
+
+    user_cache_data = read_cache(@sic.latest_user_cache_file).to_a.sort
+    assert_equal 1, user_cache_data.length
+    user_cache_data = user_cache_data.first
+
+    assert_equal @gem_repo, user_cache_data.first
+
+    gems = user_cache_data.last.source_index.map { |_,spec| spec.full_name }
+    assert_equal [@a2.full_name], gems
+  end
+
   def test_write_cache_user_no_directory
     FileUtils.rm_rf File.dirname(@sic.user_cache_file)
     FileUtils.chmod 0444, @sic.system_cache_file
Index: lib/rubygems/source_index.rb
===================================================================
--- lib/rubygems/source_index.rb	(revision 1692)
+++ lib/rubygems/source_index.rb	(working copy)
@@ -169,6 +169,7 @@
   # Add gem specifications to the source index.

   def add_specs(*gem_specs)
+    gem_specs = gem_specs.first if gem_specs.first.kind_of? Array
     gem_specs.each do |spec|
       add_spec spec
     end
Index: lib/rubygems/source_info_cache.rb
===================================================================
--- lib/rubygems/source_info_cache.rb	(revision 1692)
+++ lib/rubygems/source_info_cache.rb	(working copy)
@@ -147,7 +147,7 @@
       latest = sice.source_index.latest_specs

       new_si = Gem::SourceIndex.new
-      new_si.add_specs(*latest)
+      new_si.add_specs(latest)

       latest_sice = Gem::SourceInfoCacheEntry.new new_si, sice.size
       latest_cache_data[repo] = latest_sice