Dill issue #604

This repository contains a small example that causes dill to raise a RecursionError in certain situations. The issue is reported at uqfoundation/dill#604

I'm sure that it would be possible to devise a more minimal example, but I don't understand dill well enough to propose something simpler.

The code is structured as follows:

There are two functions - pkg.somefunc.somefunc and pkg.somemod.modfunc.
Both of these functions are exposed in the pkg namespace (refer to pkg/__init__py).
Both functions use a utility function, pkg.run.run, to execute a process.
The pkg.run.run function has a feature whereby it can perform a "dry run", where it prints out what would be executed, rather than actually executing. This feature is controlled by a module-level global variable pkg.run.DRY_RUN.
The pkg.run module has another function - pkg.run.dryrun - which can be used as a context manager to temporarily enable DRY_RUN, e.g.:
```
import pkg
import pkg.run
with pkg.run.dryrun():
    pkg.somefunc()
    pkg.modfunc()
```
The dryrun context manager function attaches a list to itself, dryrun_calls - whenever the run function performs a dry run, it adds the command that would be executed to that list. This is used for testing/diagnostic purposes.

Run with a Python environment with dill installed:

git clone https://github.com/pauldmccarthy/dill-issue.git
cd dill-issue
python fail.py