diff --git a/lib/rubygems/request_set/gem_dependency_api.rb b/lib/rubygems/request_set/gem_dependency_api.rb
index ad6e45005b..0681f8802a 100644
--- a/lib/rubygems/request_set/gem_dependency_api.rb
+++ b/lib/rubygems/request_set/gem_dependency_api.rb
@@ -435,7 +435,6 @@ Gem dependencies file #{@path} requires #{name} more than once.
     reference ||= ref
     reference ||= branch
     reference ||= tag
-    reference ||= "master"
 
     if ref && branch
       warn <<-WARNING
diff --git a/lib/rubygems/source/git.rb b/lib/rubygems/source/git.rb
index 2609a309e8..7ac685f978 100644
--- a/lib/rubygems/source/git.rb
+++ b/lib/rubygems/source/git.rb
@@ -53,7 +53,7 @@ class Gem::Source::Git < Gem::Source
     @uri = Gem::Uri.parse(repository)
     @name            = name
     @repository      = repository
-    @reference       = reference
+    @reference       = reference || "HEAD"
     @need_submodules = submodules
 
     @remote   = true
diff --git a/test/rubygems/test_gem_request_set_gem_dependency_api.rb b/test/rubygems/test_gem_request_set_gem_dependency_api.rb
index 5fd2bbb9c2..6474e500e2 100644
--- a/test/rubygems/test_gem_request_set_gem_dependency_api.rb
+++ b/test/rubygems/test_gem_request_set_gem_dependency_api.rb
@@ -95,7 +95,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[git/a master], @git_set.repositories["a"]
+    assert_equal ["git/a", nil], @git_set.repositories["a"]
 
     expected = { "a" => Gem::Requirement.create("!") }
 
@@ -107,7 +107,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[https://example@bitbucket.org/example/repository.git master],
+    assert_equal ["https://example@bitbucket.org/example/repository.git", nil],
                  @git_set.repositories["a"]
 
     expected = { "a" => Gem::Requirement.create("!") }
@@ -120,7 +120,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[https://example@bitbucket.org/example/example.git master],
+    assert_equal ["https://example@bitbucket.org/example/example.git", nil],
                  @git_set.repositories["a"]
 
     expected = { "a" => Gem::Requirement.create("!") }
@@ -145,7 +145,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[https://gist.github.com/a.git master],
+    assert_equal ["https://gist.github.com/a.git", nil],
                  @git_set.repositories["a"]
   end
 
@@ -166,7 +166,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[git/a master], @git_set.repositories["a"]
+    assert_equal ["git/a", nil], @git_set.repositories["a"]
     assert_equal %w[git/a], @git_set.need_submodules.keys
   end
 
@@ -183,7 +183,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[https://github.com/example/repository.git master],
+    assert_equal ["https://github.com/example/repository.git", nil],
                  @git_set.repositories["a"]
 
     expected = { "a" => Gem::Requirement.create("!") }
@@ -196,7 +196,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a")], @set.dependencies
 
-    assert_equal %w[https://github.com/example/example.git master],
+    assert_equal ["https://github.com/example/example.git", nil],
                  @git_set.repositories["a"]
 
     expected = { "a" => Gem::Requirement.create("!") }
@@ -609,8 +609,8 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     assert_equal [dep("a"), dep("b")], @set.dependencies
 
-    assert_equal %w[git://example/repo.git master], @git_set.repositories["a"]
-    assert_equal %w[git://example/repo.git master], @git_set.repositories["b"]
+    assert_equal ["git://example/repo.git", nil], @git_set.repositories["a"]
+    assert_equal ["git://example/repo.git", nil], @git_set.repositories["b"]
   end
 
   def test_git_source
@@ -620,7 +620,7 @@ class TestGemRequestSetGemDependencyAPI < Gem::TestCase
 
     @gda.gem "a", :example => "repo"
 
-    assert_equal %w[git://example/repo.git master], @git_set.repositories["a"]
+    assert_equal ["git://example/repo.git", nil], @git_set.repositories["a"]
   end
 
   def test_group