[Dbix-class] bug with find_or_new and update_or_insert, for postgres DB -> work around

[Patrick Weemeeuw]

Analyzing the problem a bit more, I found out that, in generic terms,
  find_or_new({ pk_col => undef })
creates an internal row, and that the successive insert fails to substitute 
the pk_col with a value from the sequence, probably because the value has 
been explicitly set.

I'm not sure whether this is a bug or 'as designed'.

Certainly, I can work around this in my application by creating a different 
path in my code depending on whether I have already a value for my PK 
specified or not. But at least one use case for find_or_new & 
update_or_insert, i.e. being able to share the same code in a web application 
both for creation and editing an entry, is not really possible.

thank you for your attention.

-- patrick