reftable: test absense of prefix matching in Reflog

Change-Id: I6705e6c57a8c080b17c7b93fdd598cf44a9d91c2
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/reftable/ReftableTest.java

@@ -567,6 +567,29 @@ public class ReftableTest {
 		}
 	}
 
+	@Test
+	public void reflogSeekPrefix() throws IOException {
+		PersonIdent who = new PersonIdent("Log", "Ger", 1500079709, -8 * 60);
+
+		ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+		ReftableWriter writer = new ReftableWriter()
+			.setMinUpdateIndex(1)
+			.setMaxUpdateIndex(1)
+			.begin(buffer);
+
+		writer.writeLog("branchname", 1, who, ObjectId.zeroId(), id(1), "branchname");
+
+		writer.finish();
+		byte[] table = buffer.toByteArray();
+
+		ReftableReader t = read(table);
+		try (LogCursor c = t.seekLog("branch", Long.MAX_VALUE)) {
+			// We find a reflog block, but the iteration won't confuse branchname
+			// and branch.
+			assertFalse(c.next());
+		}
+	}
+
 	@Test
 	public void onlyReflog() throws IOException {
 		PersonIdent who = new PersonIdent("Log", "Ger", 1500079709, -8 * 60);