The method toAbsolutePath resolve to an incoherent path when used in a process 

For example

```
ch = file(params.in)

process foo {
  input:
  file x from ch 

  "echo ${x.toAbsolutePath()}" 

}
```

It is expected that it resolves the path against the _process_ working path instead it is resolved agains the main thread execution path. 
