So, we expect there to be only 1 (or less) of these in the loop? Then why do we go through the trouble of things like 
```
if version not in top_crashes[signame][product]:
     top_crashes[signame][product][version] = {}
```
etc?

If there's only ever on crash in the TCBS we could just do:
```
if crash['signature'] == signame:
    top_crashes = {signame: {product: {version: {'currentRank': crash['currentRank'], 'plugin_count': crash['plugin_count']}}}
    break
```

All that prep work (which should be replaced with `collections.defaultdict` by the way) seems unnecessary and misleading.