Steps to reproduce:

1. Create a new pipeline job with code similar to

```
#!groovy

def myVar

node {
myVar = getMyVar()
echo "myVar is ${myVar}"
echo "Loaded pipeline script."
}

def getMyVar() {
myVar ? myVar : my_var
}
```

2. Observe CPU spike, and that job cannot be terminated

See overflow.txt for exception in CPS.