Forbid (or warn) from creation of series with same CV id

[rad96]

On try of series creation with CV id already present - forbid user from creation or at least warn and show possible duplication

Can probably be applicable to issues too

[bpepple]

Unfortunately, Comic Vine reuses their object ID's, which came to light when they started consolidating their TPB's under one series name, so making that unique could cause problems.

Currently our series model requires a series to be unique based on the following fields:

unique_together = ["publisher", "imprint", "name", "volume", "series_type"]

I have been thinking about modifying this to some like ["publisher" "name", "volume"], but I need to do some queries of the DB and subsequent testing to make sure it wouldn't break anything.

[rad96]

I know they reuse stuff, so that why I said warning would be good enough. Just to say to person "Mate, to be sure, check that out, maybe you creating duplicate - link to something"