Weird issue (NEW BUG) with Test.SetMock and body.toString() - Dreaded Uncommitted work pending

Question

Using test.setMock between test.startTest and test.stopTest

DML performs fine everywhere except:

This code fails unless the insert is not done:

sr = [Select Body From StaticResource Where Name = 'SR Name' LIMIT 1];


                    String JSONString = sr.body.toString();

                    Rule__c[] rules = new Rule__c[]{};

                    for(Rule__c r : (Rule__c[])JSON.deserialize(JSONString, Rule__c[].class)){
                        rules.add(New Rule__c(
                            Name = r.Name,
                            Name__c = r.Name__c,
                            Handled__c = r.Handled__c,
                            Text__c = r.Text__c,
                            JSON_String__c = rJSON_String__c
                        ));

                    }

                    //insert rules; 

Now, if I take the JSON string that is the body and use it alone without Querying the static resource it works fine

sr = [Select Body From StaticResource Where Name = 'SR Name' LIMIT 1];                
String JSONString = test_utils.getJSONString();

                Rule__c[] rules = new Rule__c[]{};

                for(Rule__c r : (Rule__c[])JSON.deserialize(JSONString, Rule__c[].class)){
                    rules.add(New Rule__c(
                        Name = r.Name,
                        Name__c = r.Name__c,
                        Handled__c = r.Handled__c,
                        Text__c = r.Text__c,
                        JSON_String__c = rJSON_String__c
                    ));

                }

                insert rules; 

The only difference between the two is:

1. The body.toString()
2. Both methods do indeed have records and are not null

If I do not perform that method then I do not get the uncommitted work pending.

Anyone seen this before or have any other ideas on how to get around it....