Change form fields don't appear on the same as requested in ModelAdmin.fields

[Artur Ivanov]

Hello. I've just updated django from 2.0 to 2.1.3 release and I have a problem with django admin site since.
The problem is incorrect html view of model admin fields option.

I have this code in my admin.py

@admin.register(Orders)
class OrdersAdmin(admin.ModelAdmin):
    fields = ('customer', ('order_number', 'order_date'), 'payment_day',
              'products', 'contact_pers', 'contractor', 'is_add_lic',
              'partner')

According to documentation fields order_number" and "order_date" must be on the same line because they're wraped in their own tuple. Вut it's broke since 2.1.0 release, as I guess.

To demostrate what I actually have I attached a couple of screnshots

[Tim Graham]

I haven't been able to reproduce this. Could you give a minimal project that demonstrates the issue? Ideally, you could also ​bisect to find the commit where the behavior changed.

[Simon Charette]

I haven't been able to reproduce either with the following models and admin

from django.db import models

class Author(models.Model):
    title = models.CharField(max_length=100)
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    dob = models.DateField(null=True)

from django.contrib import admin

from .models import Author

@admin.register(Author)
class AuthorAdmin(admin.ModelAdmin):
    fields = [ 
        'title',
        ('first_name', 'last_name'),
        'dob',
    ] 

The first_name and last_name appear side by side while title and dob are on their own lines.