prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Migrating to 1.1 Migration File Errors
  I am attempting to migrate to 1.1 and I am getting an error involving the migration files.
  
  ```
  Migration wagtailcore.0017_change_edit_page_permission_description dependencies reference nonexistent parent node (u'wagtailcore', u'0001_squashed_0016_change_page_url_path_to_text_field')
  ```
  
  The last migration for wagtail core in my migrations table is 0015. Since 0017 refers to 0001_squashed_0016 as a dependency and since I have not applied that migration, it's turn up as an error.
  
  I tried manually applying 0016, but the error is preventing that from happening.
  
  I know the issue queue is not intended for support questions, but I was speaking in the #django irc channel and they told me to check and see if the migrations were autogenerated. They said that normally migrations refer to the one before it and not the squashed ones.
  
  Migrating to 1.1 Migration File Errors
  I am attempting to migrate to 1.1 and I am getting an error involving the migration files.
  
  ```
  Migration wagtailcore.0017_change_edit_page_permission_description dependencies reference nonexistent parent node (u'wagtailcore', u'0001_squashed_0016_change_page_url_path_to_text_field')
  ```
  
  The last migration for wagtail core in my migrations table is 0015. Since 0017 refers to 0001_squashed_0016 as a dependency and since I have not applied that migration, it's turn up as an error.
  
  I tried manually applying 0016, but the error is preventing that from happening.
  
  I know the issue queue is not intended for support questions, but I was speaking in the #django irc channel and they told me to check and see if the migrations were autogenerated. They said that normally migrations refer to the one before it and not the squashed ones.
  
  
  </issue>
  <code>
  [start of wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py]
  1 # -*- coding: utf-8 -*-
  2 from __future__ import unicode_literals
  3 
  4 from django.db import models, migrations
  5 
  6 
  7 class Migration(migrations.Migration):
  8 
  9     dependencies = [
  10         ('wagtailcore', '0001_squashed_0016_change_page_url_path_to_text_field'),
  11     ]
  12 
  13     operations = [
  14         migrations.AlterField(
  15             model_name='grouppagepermission',
  16             name='permission_type',
  17             field=models.CharField(choices=[('add', 'Add/edit pages you own'), ('edit', 'Edit any page'), ('publish', 'Publish any page'), ('lock', 'Lock/unlock any page')], max_length=20, verbose_name='Permission type'),
  18             preserve_default=True,
  19         ),
  20     ]
  21
  [end of wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.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/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py b/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py
  --- a/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py
  +++ b/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py
  @@ -7,7 +7,7 @@
   class Migration(migrations.Migration):
   
       dependencies = [
  -        ('wagtailcore', '0001_squashed_0016_change_page_url_path_to_text_field'),
  +        ('wagtailcore', '0016_change_page_url_path_to_text_field'),
       ]
   
       operations = [
  
verification_info: {"golden_diff": "diff --git a/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py b/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py\n--- a/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py\n+++ b/wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py\n@@ -7,7 +7,7 @@\n class Migration(migrations.Migration):\n \n     dependencies = [\n-        ('wagtailcore', '0001_squashed_0016_change_page_url_path_to_text_field'),\n+        ('wagtailcore', '0016_change_page_url_path_to_text_field'),\n     ]\n \n     operations = [\n", "issue": "Migrating to 1.1 Migration File Errors\nI am attempting to migrate to 1.1 and I am getting an error involving the migration files.\n\n```\nMigration wagtailcore.0017_change_edit_page_permission_description dependencies reference nonexistent parent node (u'wagtailcore', u'0001_squashed_0016_change_page_url_path_to_text_field')\n```\n\nThe last migration for wagtail core in my migrations table is 0015. Since 0017 refers to 0001_squashed_0016 as a dependency and since I have not applied that migration, it's turn up as an error.\n\nI tried manually applying 0016, but the error is preventing that from happening.\n\nI know the issue queue is not intended for support questions, but I was speaking in the #django irc channel and they told me to check and see if the migrations were autogenerated. They said that normally migrations refer to the one before it and not the squashed ones.\n\nMigrating to 1.1 Migration File Errors\nI am attempting to migrate to 1.1 and I am getting an error involving the migration files.\n\n```\nMigration wagtailcore.0017_change_edit_page_permission_description dependencies reference nonexistent parent node (u'wagtailcore', u'0001_squashed_0016_change_page_url_path_to_text_field')\n```\n\nThe last migration for wagtail core in my migrations table is 0015. Since 0017 refers to 0001_squashed_0016 as a dependency and since I have not applied that migration, it's turn up as an error.\n\nI tried manually applying 0016, but the error is preventing that from happening.\n\nI know the issue queue is not intended for support questions, but I was speaking in the #django irc channel and they told me to check and see if the migrations were autogenerated. They said that normally migrations refer to the one before it and not the squashed ones.\n\n", "before_files": [{"content": "# -*- coding: utf-8 -*-\nfrom __future__ import unicode_literals\n\nfrom django.db import models, migrations\n\n\nclass Migration(migrations.Migration):\n\n    dependencies = [\n        ('wagtailcore', '0001_squashed_0016_change_page_url_path_to_text_field'),\n    ]\n\n    operations = [\n        migrations.AlterField(\n            model_name='grouppagepermission',\n            name='permission_type',\n            field=models.CharField(choices=[('add', 'Add/edit pages you own'), ('edit', 'Edit any page'), ('publish', 'Publish any page'), ('lock', 'Lock/unlock any page')], max_length=20, verbose_name='Permission type'),\n            preserve_default=True,\n        ),\n    ]\n", "path": "wagtail/wagtailcore/migrations/0017_change_edit_page_permission_description.py"}]}