Set python3 as default interpreter

docs/config-file/v1.rst

@@ -112,8 +112,8 @@ The ``build`` block configures specific aspects of the documentation build.
 build.image
 ```````````
 
-* Default: :djangosetting:`DOCKER_IMAGE`
-* Options: ``1.0``, ``2.0``, ``latest``
+* Default: :djangosetting:`DOCKER_DEFAULT_VERSION`
+* Options: ``stable``, ``latest``
 
 The build image to use for specific builds.
 This lets users specify a more experimental build image,
@@ -122,9 +122,8 @@ if they want to be on the cutting edge.
 Certain Python versions require a certain build image,
 as defined here:
 
-* ``1.0``: 2, 2.7, 3, 3.4
-* ``2.0``: 2, 2.7, 3, 3.5
-* ``latest``: 2, 2.7, 3, 3.3, 3.4, 3.5, 3.6
+* ``stable``: :buildpyversions:`stable`
+* ``latest``: :buildpyversions:`latest`
 
 .. code-block:: yaml
 
@@ -147,8 +146,8 @@ used for building documentation.
 python.version
 ``````````````
 
-* Default: ``2.7``
-* Options: ``2.7``, ``2``, ``3.5``, ``3``
+* Default: ``3.7``
+* Options: :buildpyversions:`latest`
 
 This is the version of Python to use when building your documentation.
 If you specify only the major version of Python,
@@ -158,7 +157,7 @@ the highest supported minor version will be selected.
 
     The supported Python versions depends on the version of the build image your
     project is using. The default build image that is used to build
-    documentation contains support for Python ``2.7`` and ``3.5``.  See the
+    documentation contains support for Python ``2.7`` and ``3.7``.  See the
     :ref:`yaml__build__image` for more information on supported Python versions.
 
 .. code-block:: yaml

readthedocs/projects/migrations/0038_change-default-python-interpreter.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.18 on 2019-02-04 16:49
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('projects', '0037_add_htmlfile'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='project',
+            name='python_interpreter',
+            field=models.CharField(choices=[('python', 'CPython 2.x'), ('python3', 'CPython 3.x')], default='python3', help_text='The Python interpreter used to create the virtual environment.', max_length=20, verbose_name='Python Interpreter'),
+        ),
+    ]

readthedocs/projects/models.py

@@ -303,7 +303,7 @@ class Project(models.Model):
         _('Python Interpreter'),
         max_length=20,
         choices=constants.PYTHON_CHOICES,
-        default='python',
+        default='python3',
         help_text=_(
             'The Python interpreter used to create the virtual '
             'environment.',

readthedocs/rtd_tests/tests/test_api.py

@@ -1468,7 +1468,7 @@ def test_get_version_by_id(self):
                 'language': 'en',
                 'name': 'Pip',
                 'programming_language': 'words',
-                'python_interpreter': 'python',
+                'python_interpreter': 'python3',
                 'repo': 'https://github.com/pypa/pip',
                 'repo_type': 'git',
                 'requirements_file': None,

readthedocs/rtd_tests/tests/test_config_integration.py

@@ -97,7 +97,7 @@ def test_python_supported_versions_default_image_1_0(self, load_config):
                 ],
                 'use_system_packages': self.project.use_system_packages,
                 'requirements_file': self.project.requirements_file,
-                'python_version': 2,
+                'python_version': 3,
                 'sphinx_configuration': mock.ANY,
                 'build_image': 'readthedocs/build:1.0',
                 'doctype': self.project.documentation_type,
@@ -112,7 +112,7 @@ def test_python_supported_versions_default_image_1_0(self, load_config):
                 path=mock.ANY,
                 env_config=expected_env_config,
         )
-        self.assertEqual(config.python.version, 2)
+        self.assertEqual(config.python.version, 3)
 
     @mock.patch('readthedocs.doc_builder.config.load_config')
     def test_python_supported_versions_image_1_0(self, load_config):
@@ -151,8 +151,8 @@ def test_python_supported_versions_image_latest(self, load_config):
     def test_python_default_version(self, load_config):
         load_config.side_effect = create_load()
         config = load_yaml_config(self.version)
-        self.assertEqual(config.python.version, 2)
-        self.assertEqual(config.python_interpreter, 'python2.7')
+        self.assertEqual(config.python.version, 3)
+        self.assertEqual(config.python_interpreter, 'python3.7')
 
     @mock.patch('readthedocs.doc_builder.config.load_config')
     def test_python_set_python_version_on_project(self, load_config):