using formfield_overrides to set CharField size causes all admin fields to use last max_length in model definition

[joebuyer@…]

Here's my example. See how title and ISBN are defined with max_length of 100 and 14. The override cause both fields to have max_length of 14 with respect to a user who is editing in the change form - a 15th character cannot be inserted into the title field.

models.py:

from django.db import models

class Book(models.Model):
    title = models.CharField(max_length=100,blank=True, null=True)
    ISBN13 = models.CharField(max_length=14,unique=True)
    def __unicode__(self):
        return self.title

admin.py:

from django.contrib import admin
from django.db import models
from django.forms import TextInput
from books.models import Book

class BookAdmin(admin.ModelAdmin):
    formfield_overrides = {
        # Django enforces maximum field length of 14 onto 'title' field when user is editing in the change form
        models.CharField: {'widget': TextInput(attrs={'size':'30'})},
        }

admin.site.register(Book,BookAdmin)