gh-157517: Don't copy HTML sources and fix sidebar sources links in docs builds (#157522)

Co-authored-by: Stan Ulbrych <stan@python.org>

Author: m-aciek

Doc/conf.py

@@ -78,6 +78,8 @@
 # and replace the values accordingly.
 # See Doc/tools/extensions/patchlevel.py
 version, release = get_version_info()
+v = get_header_version_info()
+branch = "main" if v.releaselevel == "alpha" else f"{v.major}.{v.minor}"
 
 rst_epilog = f"""
 .. |python_version_literal| replace:: ``Python {version}``
@@ -298,6 +300,7 @@
     "repository_url": repository_url or None,
     "pr_id": os.getenv("READTHEDOCS_VERSION"),
     "enable_analytics": os.getenv("PYTHON_DOCS_ENABLE_ANALYTICS"),
+    "source_branch": branch,
 }
 
 # This 'Last updated on:' timestamp is inserted at the bottom of every page.
@@ -307,6 +310,9 @@
 # Path to find HTML templates to override theme
 templates_path = ['tools/templates']
 
+# We link to sources on GitHub, so don't copy them into the HTML output.
+html_copy_source = False
+
 # Custom sidebar templates, filenames relative to this file.
 html_sidebars = {
     # Defaults taken from https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-html_sidebars
@@ -571,9 +577,6 @@
 # Options for sphinx.ext.extlinks
 # -------------------------------
 
-v = get_header_version_info()
-branch = "main" if v.releaselevel == "alpha" else f"{v.major}.{v.minor}"
-
 # This config is a dictionary of external sites,
 # mapping unique short aliases to a base URL and a prefix.
 # https://www.sphinx-doc.org/en/master/usage/extensions/extlinks.html

Doc/tools/templates/customsourcelink.html

@@ -1,4 +1,4 @@
-{%- if show_source and has_source and sourcename %}
+{%- if page_source_suffix is defined %}
   <script>
     document.addEventListener('DOMContentLoaded', () => {
         const title = document.querySelector('meta[property="og:title"]').content;
@@ -19,13 +19,13 @@ <h3>{{ _('This page') }}</h3>
       <li><a href="{{ pathto('bugs') }}">{% trans %}Report a bug{% endtrans %}</a></li>
       <li><a class="improvepage" href="{{ pathto('improve-page-nojs') }}">{% trans %}Improve this page{% endtrans %}</a></li>
       <li>
-        <a href="https://github.com/python/cpython/blob/main/Doc/{{ pagename }}.rst?plain=1"
+        <a href="https://github.com/python/cpython/blob/{{ source_branch }}/Doc/{{ pagename }}.rst?plain=1"
             rel="nofollow">{{ _('Show source') }}
         </a>
       </li>
-      {% if language != "en" %}
+      {% if language != "en" and source_branch != "main" %}
       <li>
-        <a href="https://github.com/python/python-docs-{{ language }}/blob/{{ version }}/{{ pagename }}.po?plain=1"
+        <a href="https://github.com/python/python-docs-{{ language | replace('_', '-') | lower }}/blob/{{ source_branch }}/{{ pagename }}.po?plain=1"
            rel="nofollow">{{ _('Show translation source') }}</a>
       </li>
       {% endif %}