Usage of allowed and nullable params

[mishgu]

I'm have a issues when use allowed and nullable params

Use-case abstract

 schemas = [
    {'role': {'type': 'string', 'allowed': ['agent', 'client', 'supplier']}},
    {'role': {'type': 'string', 'allowed': ['agent', 'client', 'supplier', None]}},
    {'role': {'type': 'string', 'allowed': ['agent', 'client', 'supplier'], 'nullable': True}},
    {'role': {'type': 'string', 'allowed': ['agent', 'client', 'supplier', None], 'nullable': True}},
    {'role': {'type': 'string', 'nullable': True}},
]
data = [
    {'role': 'agent'},
    {'role': None},
]

Output from cerberus

Version - 1.2
Schema # 	   Data
   1		True  False  
   2		True  False  
   3		True  False  
   4		True  True  
   5		True  True  

---

Version - 1.1
Schema # 	   Data
   1		True  False  
   2		True  False  
   3		True  True  
   4		True  True  
   5		True  True  

Bug report / Feature request

As we can see in v1.2 have different ouput with nullable param (3td schema). It looks like a bug
In my oppinion v1.1 working more properly

[funkyfuture]

see also #393 and #400. it would be helpful if you researched with git bisect which commit changed the behaviour. would you prefer that a positively defined nullable implies None to be included in allowed's constraints?

[cpforbes]

It looks like 74c015b introduced the change.

It seems that allowed needs to be added the the call to _drop_remaining_rules in order to match the 1.1 behavior.

[cpforbes]

This appears to be related to #373

[cpforbes]

After looking at the old code a bit more it seems that previously all other rules were skipped after the nullable rule if the field was null.

cerberus/cerberus/validator.py

Lines 863 to 865 in 1018ac8

	for rule in prior_rules:
	if validate_rule(rule):
	return

[funkyfuture]

no, on the contrary, no rules were skipped at all some rules caused remaining rules to be dropped, others didn't.