prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Wafer page editing fails on Django 1.8 with ImproperlyConfigured: error
  As seen on Travis, and confirmed locally, attempting to edit a page bombs out, ending with
  
  "Specifying both 'fields' and 'form_class' is not permitted."
  ImproperlyConfigured: Specifying both 'fields' and 'form_class' is not permitted.
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `wafer/pages/views.py`
  Content:
  ```
  1 from django.http import Http404
  2 from django.core.exceptions import PermissionDenied
  3 from django.views.generic import DetailView, TemplateView, UpdateView
  4 
  5 from wafer.pages.models import Page
  6 from wafer.pages.forms import PageForm
  7 
  8 
  9 class ShowPage(DetailView):
  10     template_name = 'wafer.pages/page.html'
  11     model = Page
  12 
  13 
  14 class EditPage(UpdateView):
  15     template_name = 'wafer.pages/page_form.html'
  16     model = Page
  17     form_class = PageForm
  18     fields = ['name', 'content']
  19 
  20 
  21 def slug(request, url):
  22     """Look up a page by url (which is a tree of slugs)"""
  23     page = None
  24     for slug in url.split('/'):
  25         if not slug:
  26             continue
  27         try:
  28             page = Page.objects.get(slug=slug, parent=page)
  29         except Page.DoesNotExist:
  30             raise Http404
  31 
  32     if page is None:
  33         try:
  34             page = Page.objects.get(slug='index')
  35         except Page.DoesNotExist:
  36             return TemplateView.as_view(
  37                 template_name='wafer/index.html')(request)
  38 
  39     if 'edit' in request.GET.keys():
  40         if not request.user.has_perm('pages.change_page'):
  41             raise PermissionDenied
  42         return EditPage.as_view()(request, pk=page.id)
  43 
  44     return ShowPage.as_view()(request, pk=page.id)
  45
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/wafer/pages/views.py b/wafer/pages/views.py
  --- a/wafer/pages/views.py
  +++ b/wafer/pages/views.py
  @@ -15,7 +15,6 @@
       template_name = 'wafer.pages/page_form.html'
       model = Page
       form_class = PageForm
  -    fields = ['name', 'content']
   
   
   def slug(request, url):
  
verification_info: {"golden_diff": "diff --git a/wafer/pages/views.py b/wafer/pages/views.py\n--- a/wafer/pages/views.py\n+++ b/wafer/pages/views.py\n@@ -15,7 +15,6 @@\n     template_name = 'wafer.pages/page_form.html'\n     model = Page\n     form_class = PageForm\n-    fields = ['name', 'content']\n \n \n def slug(request, url):\n", "issue": "Wafer page editing fails on Django 1.8 with ImproperlyConfigured: error\nAs seen on Travis, and confirmed locally, attempting to edit a page bombs out, ending with\n\n\"Specifying both 'fields' and 'form_class' is not permitted.\"\nImproperlyConfigured: Specifying both 'fields' and 'form_class' is not permitted.\n\n", "before_files": [{"content": "from django.http import Http404\nfrom django.core.exceptions import PermissionDenied\nfrom django.views.generic import DetailView, TemplateView, UpdateView\n\nfrom wafer.pages.models import Page\nfrom wafer.pages.forms import PageForm\n\n\nclass ShowPage(DetailView):\n    template_name = 'wafer.pages/page.html'\n    model = Page\n\n\nclass EditPage(UpdateView):\n    template_name = 'wafer.pages/page_form.html'\n    model = Page\n    form_class = PageForm\n    fields = ['name', 'content']\n\n\ndef slug(request, url):\n    \"\"\"Look up a page by url (which is a tree of slugs)\"\"\"\n    page = None\n    for slug in url.split('/'):\n        if not slug:\n            continue\n        try:\n            page = Page.objects.get(slug=slug, parent=page)\n        except Page.DoesNotExist:\n            raise Http404\n\n    if page is None:\n        try:\n            page = Page.objects.get(slug='index')\n        except Page.DoesNotExist:\n            return TemplateView.as_view(\n                template_name='wafer/index.html')(request)\n\n    if 'edit' in request.GET.keys():\n        if not request.user.has_perm('pages.change_page'):\n            raise PermissionDenied\n        return EditPage.as_view()(request, pk=page.id)\n\n    return ShowPage.as_view()(request, pk=page.id)\n", "path": "wafer/pages/views.py"}], "after_files": [{"content": "from django.http import Http404\nfrom django.core.exceptions import PermissionDenied\nfrom django.views.generic import DetailView, TemplateView, UpdateView\n\nfrom wafer.pages.models import Page\nfrom wafer.pages.forms import PageForm\n\n\nclass ShowPage(DetailView):\n    template_name = 'wafer.pages/page.html'\n    model = Page\n\n\nclass EditPage(UpdateView):\n    template_name = 'wafer.pages/page_form.html'\n    model = Page\n    form_class = PageForm\n\n\ndef slug(request, url):\n    \"\"\"Look up a page by url (which is a tree of slugs)\"\"\"\n    page = None\n    for slug in url.split('/'):\n        if not slug:\n            continue\n        try:\n            page = Page.objects.get(slug=slug, parent=page)\n        except Page.DoesNotExist:\n            raise Http404\n\n    if page is None:\n        try:\n            page = Page.objects.get(slug='index')\n        except Page.DoesNotExist:\n            return TemplateView.as_view(\n                template_name='wafer/index.html')(request)\n\n    if 'edit' in request.GET.keys():\n        if not request.user.has_perm('pages.change_page'):\n            raise PermissionDenied\n        return EditPage.as_view()(request, pk=page.id)\n\n    return ShowPage.as_view()(request, pk=page.id)\n", "path": "wafer/pages/views.py"}]}