We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
`mkdocs new` will overwrite an existing index.md file without warning.
If you run the command: `mkdocs new /path/to/dir` and `/path/to/dir/docs/index.md` already exists it will be replaced with out placeholder.


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `mkdocs/new.py`
Content:
```
1 # coding: utf-8
2 from __future__ import print_function
3 import os
4 
5 config_text = 'site_name: My Docs\n'
6 index_text = """# Welcome to MkDocs
7 
8 For full documentation visit [mkdocs.org](http://mkdocs.org).
9 
10 ## Commands
11 
12 * `mkdocs new [dir-name]` - Create a new project.
13 * `mkdocs serve` - Start the live-reloading docs server.
14 * `mkdocs build` - Build the documentation site.
15 * `mkdocs help` - Print this help message.
16 
17 ## Project layout
18 
19     mkdocs.yml    # The configuration file.
20     docs/
21         index.md  # The documentation homepage.
22         ...       # Other markdown pages, images and other files.
23 """
24 
25 
26 def new(args, options):
27     if len(args) != 1:
28         print("Usage 'mkdocs new [directory-name]'")
29         return
30 
31     output_dir = args[0]
32 
33     docs_dir = os.path.join(output_dir, 'docs')
34     config_path = os.path.join(output_dir, 'mkdocs.yml')
35     index_path = os.path.join(docs_dir, 'index.md')
36 
37     if os.path.exists(config_path):
38         print('Project already exists.')
39         return
40 
41     if not os.path.exists(output_dir):
42         print('Creating project directory: %s' % output_dir)
43         os.mkdir(output_dir)
44 
45     print('Writing config file: %s' % config_path)
46     open(config_path, 'w').write(config_text)
47 
48     print('Writing initial docs: %s' % index_path)
49     if not os.path.exists(docs_dir):
50         os.mkdir(docs_dir)
51     open(index_path, 'w').write(index_text)
52
```
--- 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/mkdocs/new.py b/mkdocs/new.py
--- a/mkdocs/new.py
+++ b/mkdocs/new.py
@@ -45,6 +45,9 @@
     print('Writing config file: %s' % config_path)
     open(config_path, 'w').write(config_text)
 
+    if os.path.exists(index_path):
+        return
+
     print('Writing initial docs: %s' % index_path)
     if not os.path.exists(docs_dir):
         os.mkdir(docs_dir)

{"golden_diff": "diff --git a/mkdocs/new.py b/mkdocs/new.py\n--- a/mkdocs/new.py\n+++ b/mkdocs/new.py\n@@ -45,6 +45,9 @@\n     print('Writing config file: %s' % config_path)\n     open(config_path, 'w').write(config_text)\n \n+    if os.path.exists(index_path):\n+        return\n+\n     print('Writing initial docs: %s' % index_path)\n     if not os.path.exists(docs_dir):\n         os.mkdir(docs_dir)\n", "issue": "`mkdocs new` will overwrite an existing index.md file without warning.\nIf you run the command: `mkdocs new /path/to/dir` and `/path/to/dir/docs/index.md` already exists it will be replaced with out placeholder.\n\n", "before_files": [{"content": "# coding: utf-8\nfrom __future__ import print_function\nimport os\n\nconfig_text = 'site_name: My Docs\\n'\nindex_text = \"\"\"# Welcome to MkDocs\n\nFor full documentation visit [mkdocs.org](http://mkdocs.org).\n\n## Commands\n\n* `mkdocs new [dir-name]` - Create a new project.\n* `mkdocs serve` - Start the live-reloading docs server.\n* `mkdocs build` - Build the documentation site.\n* `mkdocs help` - Print this help message.\n\n## Project layout\n\n    mkdocs.yml    # The configuration file.\n    docs/\n        index.md  # The documentation homepage.\n        ...       # Other markdown pages, images and other files.\n\"\"\"\n\n\ndef new(args, options):\n    if len(args) != 1:\n        print(\"Usage 'mkdocs new [directory-name]'\")\n        return\n\n    output_dir = args[0]\n\n    docs_dir = os.path.join(output_dir, 'docs')\n    config_path = os.path.join(output_dir, 'mkdocs.yml')\n    index_path = os.path.join(docs_dir, 'index.md')\n\n    if os.path.exists(config_path):\n        print('Project already exists.')\n        return\n\n    if not os.path.exists(output_dir):\n        print('Creating project directory: %s' % output_dir)\n        os.mkdir(output_dir)\n\n    print('Writing config file: %s' % config_path)\n    open(config_path, 'w').write(config_text)\n\n    print('Writing initial docs: %s' % index_path)\n    if not os.path.exists(docs_dir):\n        os.mkdir(docs_dir)\n    open(index_path, 'w').write(index_text)\n", "path": "mkdocs/new.py"}], "after_files": [{"content": "# coding: utf-8\nfrom __future__ import print_function\nimport os\n\nconfig_text = 'site_name: My Docs\\n'\nindex_text = \"\"\"# Welcome to MkDocs\n\nFor full documentation visit [mkdocs.org](http://mkdocs.org).\n\n## Commands\n\n* `mkdocs new [dir-name]` - Create a new project.\n* `mkdocs serve` - Start the live-reloading docs server.\n* `mkdocs build` - Build the documentation site.\n* `mkdocs help` - Print this help message.\n\n## Project layout\n\n    mkdocs.yml    # The configuration file.\n    docs/\n        index.md  # The documentation homepage.\n        ...       # Other markdown pages, images and other files.\n\"\"\"\n\n\ndef new(args, options):\n    if len(args) != 1:\n        print(\"Usage 'mkdocs new [directory-name]'\")\n        return\n\n    output_dir = args[0]\n\n    docs_dir = os.path.join(output_dir, 'docs')\n    config_path = os.path.join(output_dir, 'mkdocs.yml')\n    index_path = os.path.join(docs_dir, 'index.md')\n\n    if os.path.exists(config_path):\n        print('Project already exists.')\n        return\n\n    if not os.path.exists(output_dir):\n        print('Creating project directory: %s' % output_dir)\n        os.mkdir(output_dir)\n\n    print('Writing config file: %s' % config_path)\n    open(config_path, 'w').write(config_text)\n\n    if os.path.exists(index_path):\n        return\n\n    print('Writing initial docs: %s' % index_path)\n    if not os.path.exists(docs_dir):\n        os.mkdir(docs_dir)\n    open(index_path, 'w').write(index_text)\n", "path": "mkdocs/new.py"}]}