thodg/libgit2

diff --git a/include/git2/repository.h b/include/git2/repository.h
index 648667c..bf12c7a 100644
--- a/include/git2/repository.h
+++ b/include/git2/repository.h
@@ -615,11 +615,15 @@ GIT_EXTERN(int) git_repository_set_head_detached(
  * Otherwise, the HEAD will be detached and point to the peeled Commit.
  *
  * @param repo Repository pointer
+ * @param signature The identity that will used to populate the reflog entry
+ * @param log_message The one line long message to be appended to the reflog
  * @return 0 on success, GIT_EUNBORNBRANCH when HEAD points to a non existing
  * branch or an error code
  */
 GIT_EXTERN(int) git_repository_detach_head(
-	git_repository* repo);
+	git_repository* repo,
+	const git_signature *signature,
+	const char *reflog_message);
 
 typedef enum {
 	GIT_REPOSITORY_STATE_NONE,
diff --git a/src/repository.c b/src/repository.c
index 2c1b602..848aa56 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -1891,7 +1891,9 @@ cleanup:
 }
 
 int git_repository_detach_head(
-	git_repository* repo)
+	git_repository* repo,
+	const git_signature *signature,
+	const char *reflog_message)
 {
 	git_reference *old_head = NULL,
 		*new_head = NULL;
@@ -1906,7 +1908,8 @@ int git_repository_detach_head(
 	if ((error = git_object_lookup(&object, repo, git_reference_target(old_head), GIT_OBJ_COMMIT)) < 0)
 		goto cleanup;
 
-	error = git_reference_create(&new_head, repo, GIT_HEAD_FILE, git_reference_target(old_head), 1, NULL, NULL);
+	error = git_reference_create(&new_head, repo, GIT_HEAD_FILE, git_reference_target(old_head),
+			1, signature, reflog_message);
 
 cleanup:
 	git_object_free(object);
diff --git a/tests/refs/branches/delete.c b/tests/refs/branches/delete.c
index 7d1d400..ed5f162 100644
--- a/tests/refs/branches/delete.c
+++ b/tests/refs/branches/delete.c
@@ -78,7 +78,7 @@ void test_refs_branches_delete__can_delete_a_branch_pointed_at_by_detached_HEAD(
 	git_reference_free(head);
 
 	/* Detach HEAD and make it target the commit that "master" points to */
-	git_repository_detach_head(repo);
+	git_repository_detach_head(repo, NULL, NULL);
 
 	cl_git_pass(git_branch_lookup(&branch, repo, "master", GIT_BRANCH_LOCAL));
 	cl_git_pass(git_branch_delete(branch));
diff --git a/tests/repo/head.c b/tests/repo/head.c
index 127176d..c5965fa 100644
--- a/tests/repo/head.c
+++ b/tests/repo/head.c
@@ -15,21 +15,42 @@ void test_repo_head__cleanup(void)
 	cl_git_sandbox_cleanup();
 }
 
+static void check_last_reflog_entry(const char *email, const char *message)
+{
+	git_reflog *log;
+	const git_reflog_entry *entry;
+
+	cl_git_pass(git_reflog_read(&log, repo, GIT_HEAD_FILE));
+	cl_assert(git_reflog_entrycount(log) > 0);
+	entry = git_reflog_entry_byindex(log, 0);
+	if (email)
+		cl_assert_equal_s(email, git_reflog_entry_committer(entry)->email);
+	if (message)
+		cl_assert_equal_s(message, git_reflog_entry_message(entry));
+	git_reflog_free(log);
+}
+
 void test_repo_head__head_detached(void)
 {
 	git_reference *ref;
+	git_signature *sig;
 
-	cl_git_pass(git_repository_head_detached(repo));
+	cl_git_pass(git_signature_now(&sig, "Foo Bar", "foo@example.com"));
 
-	cl_git_pass(git_repository_detach_head(repo));
+	cl_assert_equal_i(false, git_repository_head_detached(repo));
 
+	cl_git_pass(git_repository_detach_head(repo, sig, "CABLE DETACHED"));
+	check_last_reflog_entry(sig->email, "CABLE DETACHED");
 	cl_assert_equal_i(true, git_repository_head_detached(repo));
 
-	/* take the reop back to it's original state */
-	cl_git_pass(git_reference_symbolic_create(&ref, repo, "HEAD", "refs/heads/master", 1, NULL, NULL));
+	/* take the repo back to it's original state */
+	cl_git_pass(git_reference_symbolic_create(&ref, repo, "HEAD", "refs/heads/master",
+				true, sig, "REATTACH"));
 	git_reference_free(ref);
 
+	check_last_reflog_entry(sig->email, "REATTACH");
 	cl_assert_equal_i(false, git_repository_head_detached(repo));
+	git_signature_free(sig);
 }
 
 void test_repo_head__unborn_head(void)
@@ -147,7 +168,7 @@ void test_repo_head__detach_head_Detaches_HEAD_and_make_it_point_to_the_peeled_c
 {
 	cl_assert_equal_i(false, git_repository_head_detached(repo));
 
-	cl_git_pass(git_repository_detach_head(repo));
+	cl_git_pass(git_repository_detach_head(repo, NULL, NULL));
 
 	assert_head_is_correctly_detached();
 }
@@ -158,7 +179,7 @@ void test_repo_head__detach_head_Fails_if_HEAD_and_point_to_a_non_commitish(void
 
 	cl_git_pass(git_reference_symbolic_create(&head, repo, GIT_HEAD_FILE, "refs/tags/point_to_blob", 1, NULL, NULL));
 
-	cl_git_fail(git_repository_detach_head(repo));
+	cl_git_fail(git_repository_detach_head(repo, NULL, NULL));
 
 	git_reference_free(head);
 }
@@ -167,7 +188,7 @@ void test_repo_head__detaching_an_unborn_branch_returns_GIT_EUNBORNBRANCH(void)
 {
 	make_head_unborn(repo, NON_EXISTING_HEAD);
 
-	cl_assert_equal_i(GIT_EUNBORNBRANCH, git_repository_detach_head(repo));
+	cl_assert_equal_i(GIT_EUNBORNBRANCH, git_repository_detach_head(repo, NULL, NULL));
 }
 
 void test_repo_head__retrieving_an_unborn_branch_returns_GIT_EUNBORNBRANCH(void)
diff --git a/tests/repo/headtree.c b/tests/repo/headtree.c
index e899ac3..79d88c0 100644
--- a/tests/repo/headtree.c
+++ b/tests/repo/headtree.c
@@ -20,7 +20,7 @@ void test_repo_headtree__cleanup(void)
 
 void test_repo_headtree__can_retrieve_the_root_tree_from_a_detached_head(void)
 {
-	cl_git_pass(git_repository_detach_head(repo));
+	cl_git_pass(git_repository_detach_head(repo, NULL, NULL));
 
 	cl_git_pass(git_repository_head_tree(&tree, repo));
 
diff --git a/tests/repo/state.c b/tests/repo/state.c
index 5a0a5f3..5e72272 100644
--- a/tests/repo/state.c
+++ b/tests/repo/state.c
@@ -37,7 +37,7 @@ void test_repo_state__none_with_HEAD_attached(void)
 
 void test_repo_state__none_with_HEAD_detached(void)
 {
-	cl_git_pass(git_repository_detach_head(_repo));
+	cl_git_pass(git_repository_detach_head(_repo, NULL, NULL));
 	assert_repo_state(GIT_REPOSITORY_STATE_NONE);
 }
 
diff --git a/tests/reset/soft.c b/tests/reset/soft.c
index 6469fce..c889c03 100644
--- a/tests/reset/soft.c
+++ b/tests/reset/soft.c
@@ -45,7 +45,7 @@ void test_reset_soft__can_reset_the_non_detached_Head_to_the_specified_commit(vo
 
 void test_reset_soft__can_reset_the_detached_Head_to_the_specified_commit(void)
 {
-	git_repository_detach_head(repo);
+	git_repository_detach_head(repo, NULL, NULL);
 
 	assert_reset_soft(true);
 }
@@ -118,7 +118,7 @@ void test_reset_soft__fails_when_merging(void)
 {
 	git_buf merge_head_path = GIT_BUF_INIT;
 
-	cl_git_pass(git_repository_detach_head(repo));
+	cl_git_pass(git_repository_detach_head(repo, NULL, NULL));
 	cl_git_pass(git_buf_joinpath(&merge_head_path, git_repository_path(repo), "MERGE_HEAD"));
 	cl_git_mkfile(git_buf_cstr(&merge_head_path), "beefbeefbeefbeefbeefbeefbeefbeefbeefbeef\n");
 
diff --git a/tests/stash/save.c b/tests/stash/save.c
index 293a89a..b5a793e 100644
--- a/tests/stash/save.c
+++ b/tests/stash/save.c
@@ -196,7 +196,7 @@ void test_stash_save__cannot_stash_against_a_bare_repository(void)
 
 void test_stash_save__can_stash_against_a_detached_head(void)
 {
-	git_repository_detach_head(repo);
+	git_repository_detach_head(repo, NULL, NULL);
 
 	cl_git_pass(git_stash_save(&stash_tip_oid, repo, signature, NULL, GIT_STASH_DEFAULT));