[SalesForce] Spring 2014 release causes “Data Not Available” when updating object as a customer portal user

This is a new issue that appeared with the Spring 2014 Salesforce update.

We have a customer portal user.

They try to update an object that they own and they created.

Yet we see a "Data Not Available" error message.

Data Not Available The data you were trying to access could not be
found. It may be due to another user deleting the data or a system
error. If you know the data is not deleted but cannot access it,
please look at our support page.

This seems to only affect the customer portal users
Also if we remove "sharing", it works.

But we want to understand why suddenly this stopped working?

The release notes https://help.salesforce.com/help/pdfs/en/salesforce_spring14_release_notes.pdf refers to sharing sets here:

Previously, a sharing set granted access to any record that has a
lookup field to an account or contact that matches the user’s account
or contact. With Spring ’14, you can also determine how access is
granted using an access mapping in the sharing set, which supports
indirect lookups from the user and target record to the account or
contact. You can determine the objects to use in the access mapping,
and they must both either point to an account or contact.

But we are seeing that even the user that created the record cannot update it.

     @isTest(SeeAllData=true) 
     private class Test1Class {
     static testMethod void validateTestCrash() {

        user u = [select id from user where username = 'cduissue1@issue1.com.issue1'];
        system.debug(u);
        system.runas(u){
            adviser_profile__c adviser_profile = [select id from adviser_profile__c limit 1];
            system.debug('qqq adviser_profile: ' + adviser_profile); 
            try {
              update adviser_profile;
            }catch (Exception e){
               system.debug('qqq3 validateTestCrash error adviser_profile: ' + adviser_profile);
            }
            system.debug('qqq2 validateTestCrash adviser_profile: ' + adviser_profile);
        }
    }
    }

Even worse, we never see either the Exception debug line NOR the final debug line.

The code simply aborts and even the salesforce log shows nothing but a simple exit, NO MESSAGE AT ALL!!!

SALESFORCE WHAT IS GOING ON???!!!