Sync the session directory after committing the renames

Syncing the files alone does not make the new names survive a crash.

test/src/test_session_commit.h

@@ -0,0 +1,24 @@
+#include "test/helpers/test_fixture.h"
+
+#include <string>
+
+class TestSessionCommit : public test_fixture {
+  CPPUNIT_TEST_SUITE(TestSessionCommit);
+
+  CPPUNIT_TEST(test_commit_publishes_all_three_files);
+  CPPUNIT_TEST(test_commit_with_fsync_publishes_all_three_files);
+
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void setUp();
+  void tearDown();
+
+  void test_commit_publishes_all_three_files();
+  void test_commit_with_fsync_publishes_all_three_files();
+
+private:
+  void commit_and_verify(bool use_fsyncdisk);
+
+  std::string m_session_dir;
+};