Tern does not account for modifications to existing methods

[nishakm]

Say if tern processes package information and could not get one set of metadata, it will store the package information in the cache with empty data. If next time around, there is an addition to the command library that allows tern to get said metadata, it will not run it because it will read the incomplete information from the cache.

1. When loading form cache, check for missing metadata. If it finds missing metadata, then run through the retrieval steps again
2. When saving to the cache, do a deep comparison of all the package metadata rather than the layer. In python one can override the class's inherited eq(self, other) to do the check. If the layers are not equal, save the layer with the packages again

[nishakm]

We can just add an option in the command line (--redo, -r) to overwrite the data that is in the cache if it exists.
This would mean writing a function to erase cached data for a particular layer.
This would also mean rewriting the flow to check if the redo flag is not set to then load data from the cache, and if yes then erase data from the cache before loading (load_from_cache function)