Fix trailing comment being counted as a separate result set.

Author: bgrainger

src/MySqlConnector/MySql.Data.MySqlClient/MySqlDataReader.cs

@@ -144,6 +144,8 @@ private async Task<ResultSet> ScanResultSetAsyncAwaited(IOBehavior ioBehavior, R
 				try
 				{
 					m_resultSetBuffered = await resultSet.ReadResultSetHeaderAsync(ioBehavior).ConfigureAwait(false);
+					if (m_resultSetBuffered.BufferState == ResultSetState.NoMoreData)
+						m_resultSetBuffered = null;
 					return m_resultSetBuffered;
 				}
 				catch (MySqlException ex) when (ex.Number == (int) MySqlErrorCode.QueryInterrupted)

tests/SideBySide/QueryTests.cs

@@ -532,6 +532,23 @@ public void ExecuteScalarReturnsDBNull()
 			}
 		}
 
+		[Fact]
+		public void TrailingCommentIsNotAResultSet()
+		{
+			using (var command = m_database.Connection.CreateCommand())
+			{
+				command.CommandText = "select 0; -- trailing comment";
+				using (var reader = command.ExecuteReader())
+				{
+					Assert.True(reader.Read());
+					Assert.Equal(0, reader.GetInt32(0));
+					Assert.False(reader.NextResult());
+					Assert.False(reader.HasRows);
+					Assert.False(reader.Read());
+				}
+			}
+		}
+
 		[Fact]
 		public void SumBytes()
 		{