fix version wrangling in docs (#7600)

Author: pmeier

.github/workflows/docs.yml

@@ -43,6 +43,14 @@ jobs:
         pip install --progress-bar=off -r requirements.txt
         echo '::endgroup::'
         
+        if [[ ${{ github.event_name }} == push && (${{ github.ref_type }} == tag || (${{ github.ref_type }} == branch && ${{ github.ref_name }} == release/*)) ]]; then
+          echo '::group::Enable version string sanitization'
+          # This environment variable just has to exist and must not be empty. The actual value is arbitrary.
+          # See docs/source/conf.py for details
+          export TORCHVISION_SANITIZE_VERSION_STR_IN_DOCS=1
+          echo '::endgroup::'
+        fi
+
         # The runner does not have sufficient memory to run with as many processes as there are
         # cores (`-j auto`). Thus, we limit to a single process (`-j 1`) here.
         sed -i -e 's/-j auto/-j 1/' Makefile

docs/source/conf.py

@@ -92,17 +92,15 @@
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
-#
-# The short X.Y version.
-version = "main (" + torchvision.__version__ + " )"
-# The full version, including alpha/beta/rc tags.
-release = "main"
-VERSION = os.environ.get("VERSION", None)
-if VERSION:
+# version: The short X.Y version.
+# release: The full version, including alpha/beta/rc tags.
+if os.environ.get("TORCHVISION_SANITIZE_VERSION_STR_IN_DOCS", None):
     # Turn 1.11.0aHASH into 1.11 (major.minor only)
-    version = ".".join(version.split(".")[:2])
+    version = release = ".".join(torchvision.__version__.split(".")[:2])
     html_title = " ".join((project, version, "documentation"))
-    release = version
+else:
+    version = f"main ({torchvision.__version__})"
+    release = "main"
 
 
 # The language for content autogenerated by Sphinx. Refer to documentation