DiscardChanges called after unsuccessful delete

i have some resource in datastore, then i deleted it and trying to delete it again. delete function return some error but netconf tries to do DiscardChanges:

2015-02-18 05:14:39,089 | WARN | entLoopGroup-2-2 | DiscardChanges | 135 - org.opendaylight.controller.config-netconf-connector - 0.2.7.Helium-SR2 | Abort failed:
java.lang.IllegalStateException: No transaction found for session netconf session id 1
at com.google.common.base.Preconditions.checkState(Preconditions.java:149)[75:com.google.guava:14.0.1]
at org.opendaylight.controller.netconf.confignetconfconnector.transactions.TransactionProvider.abortTransaction(TransactionProvider.java:130)[135:org.opendaylight.controller.config-netconf-connector:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.confignetconfconnector.operations.DiscardChanges.handleWithNoSubsequentOperations(DiscardChanges.java:59)[135:org.opendaylight.controller.config-netconf-connector:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.util.mapping.AbstractLastNetconfOperation.handle(AbstractLastNetconfOperation.java:33)[134:org.opendaylight.controller.netconf-util:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.util.mapping.AbstractNetconfOperation.handle(AbstractNetconfOperation.java:105)[134:org.opendaylight.controller.netconf-util:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.impl.osgi.NetconfOperationRouterImpl$NetconfOperationExecution.execute(NetconfOperationRouterImpl.java:221)[149:org.opendaylight.controller.netconf-impl:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.impl.osgi.NetconfOperationRouterImpl.executeOperationWithHighestPriority(NetconfOperationRouterImpl.java:154)[149:org.opendaylight.controller.netconf-impl:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.impl.osgi.NetconfOperationRouterImpl.onNetconfMessage(NetconfOperationRouterImpl.java:128)[149:org.opendaylight.controller.netconf-impl:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.impl.NetconfServerSessionListener.processDocument(NetconfServerSessionListener.java:127)[149:org.opendaylight.controller.netconf-impl:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.impl.NetconfServerSessionListener.onMessage(NetconfServerSessionListener.java:87)[149:org.opendaylight.controller.netconf-impl:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.impl.NetconfServerSessionListener.onMessage(NetconfServerSessionListener.java:32)[149:org.opendaylight.controller.netconf-impl:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.nettyutil.AbstractNetconfSession.handleMessage(AbstractNetconfSession.java:57)[142:org.opendaylight.controller.netconf-netty-util:0.2.7.Helium-SR2]
at org.opendaylight.controller.netconf.nettyutil.AbstractNetconfSession.handleMessage(AbstractNetconfSession.java:28)[142:org.opendaylight.controller.netconf-netty-util:0.2.7.Helium-SR2]
at org.opendaylight.protocol.framework.AbstractProtocolSession.channelRead0(AbstractProtocolSession.java:46)[128:org.opendaylight.controller.protocol-framework:0.5.2.Helium-SR2]
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:319)[125:io.netty.transport:4.0.23.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:163)[146:io.netty.codec:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:319)[125:io.netty.transport:4.0.23.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:163)[146:io.netty.codec:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:319)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:787)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.local.LocalChannel.finishPeerRead(LocalChannel.java:326)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.local.LocalChannel.access$400(LocalChannel.java:45)[125:io.netty.transport:4.0.23.Final]
at io.netty.channel.local.LocalChannel$5.run(LocalChannel.java:312)[125:io.netty.transport:4.0.23.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:380)[126:io.netty.common:4.0.23.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:357)[125:io.netty.transport:4.0.23.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116)[126:io.netty.common:4.0.23.Final]
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)[126:io.netty.common:4.0.23.Final]
at java.lang.Thread.run(Unknown Source)[:1.7.0_60]
2015-02-18 05:14:39,109 | WARN | oupCloseable-6-1 | NetconfDeviceCommunicator | 165 - org.opendaylight.controller.sal-netconf-connector - 1.1.2.Helium-SR2 | RemoteDevice

: Error reply from remote device, request: <rpc message-id="m-221" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<discard-changes/>
</rpc>
, response: <rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="m-221">
<rpc-error>
<error-type>application</error-type>
<error-tag>operation-failed</error-tag>
<error-severity>error</error-severity>
<error-message>No transaction found for session netconf session id 1</error-message>
<error-info>
<operation_failed>Operation failed. Use 'get-config' or 'edit-config' before triggering 'discard-changes' operation</operation_failed>
</error-info>
</rpc-error>
</rpc-reply>