prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Change Mezzanine Form to Disallow Username Changes
  **Describe the feature you'd like and what it will do**
  The internal mezzanine form for the admin account should be altered to no longer allow username changes if possible, since doing so breaks the resource. 
  
  
  **Why is this feature important?**
  This will be policy moving forward, that usernames cannot be changed. 
  I will work with Scott to see if this change is feasible. 
  
  
  </issue>
  <code>
  [start of hs_core/admin.py]
  1 from django import forms
  2 from django.contrib.auth.admin import UserAdmin
  3 from django.contrib.auth.forms import UserCreationForm
  4 from django.contrib.gis import admin
  5 from django.contrib.contenttypes.admin import GenericTabularInline
  6 from django.utils.translation import ugettext_lazy as _
  7 
  8 from .models import *
  9 
  10 
  11 class UserCreationFormExtended(UserCreationForm):
  12     def __init__(self, *args, **kwargs):
  13         super(UserCreationFormExtended, self).__init__(*args, **kwargs)
  14         self.fields['email'] = forms.EmailField(label=_("E-mail"), max_length=75)
  15 
  16 UserAdmin.add_form = UserCreationFormExtended
  17 UserAdmin.add_fieldsets = (
  18     (None, {
  19         'classes': ('wide',),
  20         'fields': ('email', 'username', 'password1', 'password2',)
  21     }),
  22 )
  23 UserAdmin.list_display = [
  24     'username', 'email', 'first_name', 'last_name', 'is_staff',
  25     'is_active', 'date_joined', 'last_login'
  26 ]
  27 
  28 class InlineResourceFiles(GenericTabularInline):
  29     model = ResourceFile
  30 
  31 admin.site.unregister(User)
  32 admin.site.register(User, UserAdmin)
  33 admin.site.unregister(GenericResource)
  34
  [end of hs_core/admin.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/hs_core/admin.py b/hs_core/admin.py
  --- a/hs_core/admin.py
  +++ b/hs_core/admin.py
  @@ -14,6 +14,7 @@
           self.fields['email'] = forms.EmailField(label=_("E-mail"), max_length=75)
   
   UserAdmin.add_form = UserCreationFormExtended
  +UserAdmin.readonly_fields = ('username',)
   UserAdmin.add_fieldsets = (
       (None, {
           'classes': ('wide',),
  
verification_info: {"golden_diff": "diff --git a/hs_core/admin.py b/hs_core/admin.py\n--- a/hs_core/admin.py\n+++ b/hs_core/admin.py\n@@ -14,6 +14,7 @@\n         self.fields['email'] = forms.EmailField(label=_(\"E-mail\"), max_length=75)\n \n UserAdmin.add_form = UserCreationFormExtended\n+UserAdmin.readonly_fields = ('username',)\n UserAdmin.add_fieldsets = (\n     (None, {\n         'classes': ('wide',),\n", "issue": "Change Mezzanine Form to Disallow Username Changes\n**Describe the feature you'd like and what it will do**\r\nThe internal mezzanine form for the admin account should be altered to no longer allow username changes if possible, since doing so breaks the resource. \r\n\r\n\r\n**Why is this feature important?**\r\nThis will be policy moving forward, that usernames cannot be changed. \r\nI will work with Scott to see if this change is feasible. \r\n\n", "before_files": [{"content": "from django import forms\nfrom django.contrib.auth.admin import UserAdmin\nfrom django.contrib.auth.forms import UserCreationForm\nfrom django.contrib.gis import admin\nfrom django.contrib.contenttypes.admin import GenericTabularInline\nfrom django.utils.translation import ugettext_lazy as _\n\nfrom .models import *\n\n\nclass UserCreationFormExtended(UserCreationForm):\n    def __init__(self, *args, **kwargs):\n        super(UserCreationFormExtended, self).__init__(*args, **kwargs)\n        self.fields['email'] = forms.EmailField(label=_(\"E-mail\"), max_length=75)\n\nUserAdmin.add_form = UserCreationFormExtended\nUserAdmin.add_fieldsets = (\n    (None, {\n        'classes': ('wide',),\n        'fields': ('email', 'username', 'password1', 'password2',)\n    }),\n)\nUserAdmin.list_display = [\n    'username', 'email', 'first_name', 'last_name', 'is_staff',\n    'is_active', 'date_joined', 'last_login'\n]\n\nclass InlineResourceFiles(GenericTabularInline):\n    model = ResourceFile\n\nadmin.site.unregister(User)\nadmin.site.register(User, UserAdmin)\nadmin.site.unregister(GenericResource)\n", "path": "hs_core/admin.py"}]}