Stop escaping custom response errors

[pdpinch]

I thought we had already fixed this, but I guess not:

With a custom problem like:

<problem>
<script type="loncapa/python">
def grader(expect, answer):
    raise ValueError("It's not working again!")
</script>
<customresponse cfn="grader" expect="2*x">
<textline />
</customresponse>
</problem>

The response is:

┆Issue is synchronized with this Trello card by Unito

[Ayub-Khan]

@pdpinch i was not able to reproduce this against mitx/master or mitx/hawthorn-release.

[pdpinch]

@jolyonb can you reproduce this on edx.org? What about Residential MITx?

[jolyonb]

I can reproduce this on edge.edx.org and on studio.mitx.mit.edu. Here is a screenshot, using the above:

[jolyonb]

Note that the issue here is that the apostrophe is being escaped, when it shouldn't be.

[pdpinch]

Ok, I can't reproduce this in devstack, but I definitely see it happening on edge, on stage.edx.org and on studio-staging.mitx. I think perhaps that in devstack the codejail is disabled, so that the python is run without being jailed. This leads to one less level of escaping in devstack (or maybe 2) in the response, so it's handled well. In production, it's escape more times, so the unescaping isn't effective.

I'm not sure what the fix is yet. Maybe the first thing to do is to figure out how to configure devstack similarly to a production install.

[jolyonb]

That could well explain why this cropped up again. We fixed it in the devstack, but never tested it in production. I suspect that the fix we put in undid a second level of escaping...

[pdpinch]

@blarghmatey tells me that our codejail settings for Residential MITx are at https://github.com/mitodl/salt-ops/blob/master/pillar/edx/ansible_vars/residential.sls#L328

The current theory is that if one replicates those settings on their devstack, they should be able to reproduce the error.