[RFC] Error plugin separate 400 / 500

[joelwurtz]

Q	A
Bug?	no
New Feature?	yes

Actual Behavior

Actually the error plugin always throws an exception on status >= 400

Expected Behavior

It would be better to add options for only throwing status >= 500 or 500 > status >= 400

As an example when i want to retry requests on a web server, i may want to retry only on server errors and not on client errors.

Also 400 errors are often not errors and more a normal comportement that i need to take into account, as i would like to know if some resource exists on the server i don't want to deal that with an exception having a 404 may be a normal thing for me.

However 500 errors are never normals so i want to treat them specialy compared to the 400 ones.

WDYT ?

[Nyholm]

Sure, Let's add some config to the error plugin.