We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
[AIRFLOW-3014] Fix multiple alembic heads
Make sure you have checked _all_ steps below.

### Jira

- [ ] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title. For example, "\[AIRFLOW-XXX\] My Airflow PR"
  - https://issues.apache.org/jira/browse/AIRFLOW-6224
  - In case you are fixing a typo in the documentation you can prepend your commit with \[AIRFLOW-XXX\], code changes always need a Jira issue.
  - In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvements+Proposals)).
  - In case you are adding a dependency, check if the license complies with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x).

### Description

- [ ] Here are some details about my PR, including screenshots of any UI changes:

### Tests

- [ ] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:

### Commits

- [ ] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)":
  1. Subject is separated from body by a blank line
  1. Subject is limited to 50 characters (not including Jira issue reference)
  1. Subject does not end with a period
  1. Subject uses the imperative mood ("add", not "adding")
  1. Body wraps at 72 characters
  1. Body explains "what" and "why", not "how"

### Documentation

- [ ] In case of new functionality, my PR adds documentation that describes how to use it.
  - All the public functions and the classes in the PR contain docstrings that explain what it does
  - If you implement backwards incompatible changes, please leave a note in the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so we can assign it to a appropriate release


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py`
Content:
```
1 #
2 # Licensed to the Apache Software Foundation (ASF) under one
3 # or more contributor license agreements.  See the NOTICE file
4 # distributed with this work for additional information
5 # regarding copyright ownership.  The ASF licenses this file
6 # to you under the Apache License, Version 2.0 (the
7 # "License"); you may not use this file except in compliance
8 # with the License.  You may obtain a copy of the License at
9 #
10 #   http://www.apache.org/licenses/LICENSE-2.0
11 #
12 # Unless required by applicable law or agreed to in writing,
13 # software distributed under the License is distributed on an
14 # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 # KIND, either express or implied.  See the License for the
16 # specific language governing permissions and limitations
17 # under the License.
18 
19 """Increase length of password column in connection table
20 
21 Revision ID: c1840b4bcf1a
22 Revises: 004c1210f153
23 Create Date: 2019-10-02 16:56:54.865550
24 
25 """
26 
27 import sqlalchemy as sa
28 from alembic import op
29 
30 # revision identifiers, used by Alembic.
31 revision = 'c1840b4bcf1a'
32 down_revision = '004c1210f153'
33 branch_labels = None
34 depends_on = None
35 
36 
37 def upgrade():
38     conn = op.get_bind()
39     if conn.dialect.name == 'sqlite':
40         # SQLite does not allow column modifications so we need to skip this migration
41         return
42 
43     op.alter_column(table_name='connection',
44                     column_name='password',
45                     type_=sa.String(length=5000))
46 
47 
48 def downgrade():
49     # Can't be undone
50     pass
51
```
--- 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/airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py b/airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py
deleted file mode 100644
--- a/airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py
+++ /dev/null
@@ -1,50 +0,0 @@
-#
-# Licensed to the Apache Software Foundation (ASF) under one
-# or more contributor license agreements.  See the NOTICE file
-# distributed with this work for additional information
-# regarding copyright ownership.  The ASF licenses this file
-# to you under the Apache License, Version 2.0 (the
-# "License"); you may not use this file except in compliance
-# with the License.  You may obtain a copy of the License at
-#
-#   http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing,
-# software distributed under the License is distributed on an
-# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-# KIND, either express or implied.  See the License for the
-# specific language governing permissions and limitations
-# under the License.
-
-"""Increase length of password column in connection table
-
-Revision ID: c1840b4bcf1a
-Revises: 004c1210f153
-Create Date: 2019-10-02 16:56:54.865550
-
-"""
-
-import sqlalchemy as sa
-from alembic import op
-
-# revision identifiers, used by Alembic.
-revision = 'c1840b4bcf1a'
-down_revision = '004c1210f153'
-branch_labels = None
-depends_on = None
-
-
-def upgrade():
-    conn = op.get_bind()
-    if conn.dialect.name == 'sqlite':
-        # SQLite does not allow column modifications so we need to skip this migration
-        return
-
-    op.alter_column(table_name='connection',
-                    column_name='password',
-                    type_=sa.String(length=5000))
-
-
-def downgrade():
-    # Can't be undone
-    pass

{"golden_diff": "diff --git a/airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py b/airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py\ndeleted file mode 100644\n--- a/airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py\n+++ /dev/null\n@@ -1,50 +0,0 @@\n-#\n-# Licensed to the Apache Software Foundation (ASF) under one\n-# or more contributor license agreements.  See the NOTICE file\n-# distributed with this work for additional information\n-# regarding copyright ownership.  The ASF licenses this file\n-# to you under the Apache License, Version 2.0 (the\n-# \"License\"); you may not use this file except in compliance\n-# with the License.  You may obtain a copy of the License at\n-#\n-#   http://www.apache.org/licenses/LICENSE-2.0\n-#\n-# Unless required by applicable law or agreed to in writing,\n-# software distributed under the License is distributed on an\n-# \"AS IS\" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY\n-# KIND, either express or implied.  See the License for the\n-# specific language governing permissions and limitations\n-# under the License.\n-\n-\"\"\"Increase length of password column in connection table\n-\n-Revision ID: c1840b4bcf1a\n-Revises: 004c1210f153\n-Create Date: 2019-10-02 16:56:54.865550\n-\n-\"\"\"\n-\n-import sqlalchemy as sa\n-from alembic import op\n-\n-# revision identifiers, used by Alembic.\n-revision = 'c1840b4bcf1a'\n-down_revision = '004c1210f153'\n-branch_labels = None\n-depends_on = None\n-\n-\n-def upgrade():\n-    conn = op.get_bind()\n-    if conn.dialect.name == 'sqlite':\n-        # SQLite does not allow column modifications so we need to skip this migration\n-        return\n-\n-    op.alter_column(table_name='connection',\n-                    column_name='password',\n-                    type_=sa.String(length=5000))\n-\n-\n-def downgrade():\n-    # Can't be undone\n-    pass\n", "issue": "[AIRFLOW-3014] Fix multiple alembic heads\nMake sure you have checked _all_ steps below.\r\n\r\n### Jira\r\n\r\n- [ ] My PR addresses the following [Airflow Jira](https://issues.apache.org/jira/browse/AIRFLOW/) issues and references them in the PR title. For example, \"\\[AIRFLOW-XXX\\] My Airflow PR\"\r\n  - https://issues.apache.org/jira/browse/AIRFLOW-6224\r\n  - In case you are fixing a typo in the documentation you can prepend your commit with \\[AIRFLOW-XXX\\], code changes always need a Jira issue.\r\n  - In case you are proposing a fundamental code change, you need to create an Airflow Improvement Proposal ([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvements+Proposals)).\r\n  - In case you are adding a dependency, check if the license complies with the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x).\r\n\r\n### Description\r\n\r\n- [ ] Here are some details about my PR, including screenshots of any UI changes:\r\n\r\n### Tests\r\n\r\n- [ ] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:\r\n\r\n### Commits\r\n\r\n- [ ] My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from \"[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)\":\r\n  1. Subject is separated from body by a blank line\r\n  1. Subject is limited to 50 characters (not including Jira issue reference)\r\n  1. Subject does not end with a period\r\n  1. Subject uses the imperative mood (\"add\", not \"adding\")\r\n  1. Body wraps at 72 characters\r\n  1. Body explains \"what\" and \"why\", not \"how\"\r\n\r\n### Documentation\r\n\r\n- [ ] In case of new functionality, my PR adds documentation that describes how to use it.\r\n  - All the public functions and the classes in the PR contain docstrings that explain what it does\r\n  - If you implement backwards incompatible changes, please leave a note in the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so we can assign it to a appropriate release\r\n\n", "before_files": [{"content": "#\n# Licensed to the Apache Software Foundation (ASF) under one\n# or more contributor license agreements.  See the NOTICE file\n# distributed with this work for additional information\n# regarding copyright ownership.  The ASF licenses this file\n# to you under the Apache License, Version 2.0 (the\n# \"License\"); you may not use this file except in compliance\n# with the License.  You may obtain a copy of the License at\n#\n#   http://www.apache.org/licenses/LICENSE-2.0\n#\n# Unless required by applicable law or agreed to in writing,\n# software distributed under the License is distributed on an\n# \"AS IS\" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY\n# KIND, either express or implied.  See the License for the\n# specific language governing permissions and limitations\n# under the License.\n\n\"\"\"Increase length of password column in connection table\n\nRevision ID: c1840b4bcf1a\nRevises: 004c1210f153\nCreate Date: 2019-10-02 16:56:54.865550\n\n\"\"\"\n\nimport sqlalchemy as sa\nfrom alembic import op\n\n# revision identifiers, used by Alembic.\nrevision = 'c1840b4bcf1a'\ndown_revision = '004c1210f153'\nbranch_labels = None\ndepends_on = None\n\n\ndef upgrade():\n    conn = op.get_bind()\n    if conn.dialect.name == 'sqlite':\n        # SQLite does not allow column modifications so we need to skip this migration\n        return\n\n    op.alter_column(table_name='connection',\n                    column_name='password',\n                    type_=sa.String(length=5000))\n\n\ndef downgrade():\n    # Can't be undone\n    pass\n", "path": "airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py"}], "after_files": [{"content": null, "path": "airflow/migrations/versions/c1840b4bcf1a_increase_length_of_password_column_in_.py"}]}