We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Ensure rotation column == 'False' during migration.
Null values creates problems during validation.

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `lemur/migrations/versions/131ec6accff5_.py`
Content:
```
1 """Ensuring we have endpoint updated times and certificate rotation availability.
2 
3 Revision ID: 131ec6accff5
4 Revises: e3691fc396e9
5 Create Date: 2016-12-07 17:29:42.049986
6 
7 """
8 
9 # revision identifiers, used by Alembic.
10 revision = '131ec6accff5'
11 down_revision = 'e3691fc396e9'
12 
13 from alembic import op
14 import sqlalchemy as sa
15 
16 
17 def upgrade():
18     # ### commands auto generated by Alembic - please adjust! ###
19     op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=True))
20     op.add_column('endpoints', sa.Column('last_updated', sa.DateTime(), server_default=sa.text('now()'), nullable=False))
21     # ### end Alembic commands ###
22 
23 
24 def downgrade():
25     # ### commands auto generated by Alembic - please adjust! ###
26     op.drop_column('endpoints', 'last_updated')
27     op.drop_column('certificates', 'rotation')
28     # ### end Alembic commands ###
29
```
--- 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/lemur/migrations/versions/131ec6accff5_.py b/lemur/migrations/versions/131ec6accff5_.py
--- a/lemur/migrations/versions/131ec6accff5_.py
+++ b/lemur/migrations/versions/131ec6accff5_.py
@@ -16,7 +16,7 @@
 
 def upgrade():
     # ### commands auto generated by Alembic - please adjust! ###
-    op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=True))
+    op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=False, server_default=False))
     op.add_column('endpoints', sa.Column('last_updated', sa.DateTime(), server_default=sa.text('now()'), nullable=False))
     # ### end Alembic commands ###

{"golden_diff": "diff --git a/lemur/migrations/versions/131ec6accff5_.py b/lemur/migrations/versions/131ec6accff5_.py\n--- a/lemur/migrations/versions/131ec6accff5_.py\n+++ b/lemur/migrations/versions/131ec6accff5_.py\n@@ -16,7 +16,7 @@\n \n def upgrade():\n     # ### commands auto generated by Alembic - please adjust! ###\n-    op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=True))\n+    op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=False, server_default=False))\n     op.add_column('endpoints', sa.Column('last_updated', sa.DateTime(), server_default=sa.text('now()'), nullable=False))\n     # ### end Alembic commands ###\n", "issue": "Ensure rotation column == 'False' during migration.\nNull values creates problems during validation.\n", "before_files": [{"content": "\"\"\"Ensuring we have endpoint updated times and certificate rotation availability.\n\nRevision ID: 131ec6accff5\nRevises: e3691fc396e9\nCreate Date: 2016-12-07 17:29:42.049986\n\n\"\"\"\n\n# revision identifiers, used by Alembic.\nrevision = '131ec6accff5'\ndown_revision = 'e3691fc396e9'\n\nfrom alembic import op\nimport sqlalchemy as sa\n\n\ndef upgrade():\n    # ### commands auto generated by Alembic - please adjust! ###\n    op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=True))\n    op.add_column('endpoints', sa.Column('last_updated', sa.DateTime(), server_default=sa.text('now()'), nullable=False))\n    # ### end Alembic commands ###\n\n\ndef downgrade():\n    # ### commands auto generated by Alembic - please adjust! ###\n    op.drop_column('endpoints', 'last_updated')\n    op.drop_column('certificates', 'rotation')\n    # ### end Alembic commands ###\n", "path": "lemur/migrations/versions/131ec6accff5_.py"}], "after_files": [{"content": "\"\"\"Ensuring we have endpoint updated times and certificate rotation availability.\n\nRevision ID: 131ec6accff5\nRevises: e3691fc396e9\nCreate Date: 2016-12-07 17:29:42.049986\n\n\"\"\"\n\n# revision identifiers, used by Alembic.\nrevision = '131ec6accff5'\ndown_revision = 'e3691fc396e9'\n\nfrom alembic import op\nimport sqlalchemy as sa\n\n\ndef upgrade():\n    # ### commands auto generated by Alembic - please adjust! ###\n    op.add_column('certificates', sa.Column('rotation', sa.Boolean(), nullable=False, server_default=False))\n    op.add_column('endpoints', sa.Column('last_updated', sa.DateTime(), server_default=sa.text('now()'), nullable=False))\n    # ### end Alembic commands ###\n\n\ndef downgrade():\n    # ### commands auto generated by Alembic - please adjust! ###\n    op.drop_column('endpoints', 'last_updated')\n    op.drop_column('certificates', 'rotation')\n    # ### end Alembic commands ###\n", "path": "lemur/migrations/versions/131ec6accff5_.py"}]}