Update guide to merge files from 3.8

Author: humitos

.overrides/upgrade-python-version.rst

@@ -0,0 +1,36 @@
+=======================================
+ How to update to a new Python version
+=======================================
+
+We are currently in branch 3.7, and we want to update the strings from 3.8.
+
+
+#. Fetch the `lastet commit of 3.8 branch <https://github.com/python/cpython/commit/70fe95cdc9ac1b00d4f86b7525dca80caf7003e1>`_::
+
+   git fetch --depth 1 origin 70fe95cdc9ac1b00d4f86b7525dca80caf7003e1
+
+#. Checkout that commit locally::
+
+   git checkout 70fe95cdc9ac1b00d4f86b7525dca80caf7003e1
+
+#. Create the .po files from the new source code. This will generate all the .po files for version 3.8::
+
+   SPHINX_GETTEXT=True sphinx-build -j auto -b gettext -d _build/doctrees . ../pot
+
+#. Now we have to merge our current translation .po files with the new .po files that come from upstream::
+
+   pomerge --from-files **/*.po --to-files ../pot/**/*.pot
+
+   .. note::
+
+      In ../pot, we will have the new .pot files with new strings from 3.8 branch,
+      with all the translations from our current 3.7 branch.
+      If there wasn't a translation found, it is left unstranlated.
+
+#. Remove `python-docs-cpython/` prefix::
+
+   sed -i **/*.pot -e "s|python-docs-es/cpython/||g"
+
+#. Rename all the .pot files to .po files::
+
+#. Move all the newly pot files created to our repository::

conf.py

@@ -35,20 +35,21 @@
 os.system('ln -nfs `pwd` cpython/locales/es/LC_MESSAGES')
 
 
-# Override all the files from ``.overrides`` directory
-import glob
-for root, dirs, files in os.walk('.overrides'):
-    for fname in files:
-        if fname == 'README.rst' and root == '.overrides':
-            continue
-        destroot = root.replace('.overrides', '').lstrip('/')
-        outputdir = os.path.join(
-            'cpython',
-            'Doc',
-            destroot,
-            fname,
-        )
-        os.system(f'ln -nfs `pwd`/{root}/{fname} {outputdir}')
+if not os.environ.get('SPHINX_GETTEXT') == 'True':
+    # Override all the files from ``.overrides`` directory
+    import glob
+    for root, dirs, files in os.walk('.overrides'):
+        for fname in files:
+            if fname == 'README.rst' and root == '.overrides':
+                continue
+            destroot = root.replace('.overrides', '').lstrip('/')
+            outputdir = os.path.join(
+                'cpython',
+                'Doc',
+                destroot,
+                fname,
+            )
+            os.system(f'ln -nfs `pwd`/{root}/{fname} {outputdir}')
 
 gettext_compact = False
 locale_dirs = ['../locales', 'cpython/locales']  # relative to the sourcedir
@@ -62,6 +63,12 @@ def add_contributing_banner(app, doctree):
         This way, we can easily communicate people to help with the translation,
         pointing them to different resources.
         """
+
+        if app.builder.format != 'html':
+            # Do not include the banner when building with other formats
+            # (this is useful when using -b gettext)
+            return
+
         from docutils import nodes, core
 
         message = '¡Ayúdanos a traducir la documentación oficial de Python al Español! ' \