We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Fix intent default value to all examples, migration intent required


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `bothub/common/migrations/0021_auto_20180921_1259.py`
Content:
```
1 # Generated by Django 2.0.6 on 2018-09-21 12:59
2 
3 import django.core.validators
4 from django.db import migrations, models
5 import re
6 
7 
8 class Migration(migrations.Migration):
9 
10     dependencies = [
11         ('common', '0020_auto_20180813_1320'),
12     ]
13 
14     operations = [
15         migrations.AlterField(
16             model_name='repositoryexample',
17             name='intent',
18             field=models.CharField(default='no_intent', help_text='Example intent reference', max_length=64, validators=[django.core.validators.RegexValidator(re.compile('^[-a-z0-9_]+\\Z'), 'Enter a valid value consisting of lowercase letters, numbers, underscores or hyphens.', 'invalid')], verbose_name='intent'),
19         ),
20     ]
21
```
--- 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()

```

diff --git a/bothub/common/migrations/0021_auto_20180921_1259.py b/bothub/common/migrations/0021_auto_20180921_1259.py
--- a/bothub/common/migrations/0021_auto_20180921_1259.py
+++ b/bothub/common/migrations/0021_auto_20180921_1259.py
@@ -5,6 +5,11 @@
 import re
 
 
+def populate_empty_intent(apps, *args):
+    RepositoryExample = apps.get_model('common', 'RepositoryExample')
+    RepositoryExample.objects.filter(intent='').update(intent='no_intent')
+
+
 class Migration(migrations.Migration):
 
     dependencies = [
@@ -17,4 +22,5 @@
             name='intent',
             field=models.CharField(default='no_intent', help_text='Example intent reference', max_length=64, validators=[django.core.validators.RegexValidator(re.compile('^[-a-z0-9_]+\\Z'), 'Enter a valid value consisting of lowercase letters, numbers, underscores or hyphens.', 'invalid')], verbose_name='intent'),
         ),
+        migrations.RunPython(populate_empty_intent),
     ]

{"golden_diff": "diff --git a/bothub/common/migrations/0021_auto_20180921_1259.py b/bothub/common/migrations/0021_auto_20180921_1259.py\n--- a/bothub/common/migrations/0021_auto_20180921_1259.py\n+++ b/bothub/common/migrations/0021_auto_20180921_1259.py\n@@ -5,6 +5,11 @@\n import re\n \n \n+def populate_empty_intent(apps, *args):\n+    RepositoryExample = apps.get_model('common', 'RepositoryExample')\n+    RepositoryExample.objects.filter(intent='').update(intent='no_intent')\n+\n+\n class Migration(migrations.Migration):\n \n     dependencies = [\n@@ -17,4 +22,5 @@\n             name='intent',\n             field=models.CharField(default='no_intent', help_text='Example intent reference', max_length=64, validators=[django.core.validators.RegexValidator(re.compile('^[-a-z0-9_]+\\\\Z'), 'Enter a valid value consisting of lowercase letters, numbers, underscores or hyphens.', 'invalid')], verbose_name='intent'),\n         ),\n+        migrations.RunPython(populate_empty_intent),\n     ]\n", "issue": "Fix intent default value to all examples, migration intent required\n\n", "before_files": [{"content": "# Generated by Django 2.0.6 on 2018-09-21 12:59\n\nimport django.core.validators\nfrom django.db import migrations, models\nimport re\n\n\nclass Migration(migrations.Migration):\n\n    dependencies = [\n        ('common', '0020_auto_20180813_1320'),\n    ]\n\n    operations = [\n        migrations.AlterField(\n            model_name='repositoryexample',\n            name='intent',\n            field=models.CharField(default='no_intent', help_text='Example intent reference', max_length=64, validators=[django.core.validators.RegexValidator(re.compile('^[-a-z0-9_]+\\\\Z'), 'Enter a valid value consisting of lowercase letters, numbers, underscores or hyphens.', 'invalid')], verbose_name='intent'),\n        ),\n    ]\n", "path": "bothub/common/migrations/0021_auto_20180921_1259.py"}], "after_files": [{"content": "# Generated by Django 2.0.6 on 2018-09-21 12:59\n\nimport django.core.validators\nfrom django.db import migrations, models\nimport re\n\n\ndef populate_empty_intent(apps, *args):\n    RepositoryExample = apps.get_model('common', 'RepositoryExample')\n    RepositoryExample.objects.filter(intent='').update(intent='no_intent')\n\n\nclass Migration(migrations.Migration):\n\n    dependencies = [\n        ('common', '0020_auto_20180813_1320'),\n    ]\n\n    operations = [\n        migrations.AlterField(\n            model_name='repositoryexample',\n            name='intent',\n            field=models.CharField(default='no_intent', help_text='Example intent reference', max_length=64, validators=[django.core.validators.RegexValidator(re.compile('^[-a-z0-9_]+\\\\Z'), 'Enter a valid value consisting of lowercase letters, numbers, underscores or hyphens.', 'invalid')], verbose_name='intent'),\n        ),\n        migrations.RunPython(populate_empty_intent),\n    ]\n", "path": "bothub/common/migrations/0021_auto_20180921_1259.py"}]}