I've tried to use docker agent via dockerfile property. But it seems it does not work when I use dir property like this:

```
agent {
dockerfile {
dir "Docker/debian-6"
label "docker"
}
}
```

Caveat is that Jenkins Master machine is Windows Server 2012. I've took a look at pipeline.log artifact and see that docker-workflow-plugin use path with backslash.

It's part of this pipeline.log:

```

[Pipeline] withEnv

[Pipeline] {

[Pipeline] stage

[Pipeline] { (Declarative: Agent Setup)

[Pipeline] readFile

[Pipeline] sh [ORG_SUBMODULE_TEST_1.0-RGUTA527APORVGDNZVI75RGUDPT4CP6FYZ65GVGMMHAULYZFWKMQ] Running shell script + docker build -t 3d071d6ed0f35961fba3596ce9e2d38536e0657a -f Docker/debian-6\Dockerfile Docker/debian-6 unable to prepare context: unable to evaluate symlinks in Dockerfile path: lstat /home/user/jenkins/workspace/ORG_SUBMODULE_TEST_1.0-RGUTA527APORVGDNZVI75RGUDPT4CP6FYZ65GVGMMHAULYZFWKMQ/Docker/debian-6\Dockerfile: no such file or directory

[Pipeline] }

[Pipeline] // stage

[Pipeline] }

[Pipeline] // withEnv

[Pipeline] }

```