chore(ci): Skip diffs if not on default branch

.github/workflows/gh-pages.yaml

@@ -43,6 +43,8 @@ jobs:
         run: |
           tox -e spec-docs
           touch .tox/docs/.nojekyll
+        env:
+          DOCC_SKIP_DIFFS: ${{ (github.event_name != 'push' || github.ref_name != github.event.repository.default_branch) && '1' || '' }}
 
       - name: Upload Pages Artifact
         id: artifact

src/ethereum_spec_tools/docc.py

@@ -19,6 +19,7 @@
 
 import dataclasses
 import logging
+import os
 from collections import defaultdict
 from itertools import tee, zip_longest
 from pathlib import PurePath
@@ -89,6 +90,10 @@ def discover(self, known: FrozenSet[T]) -> Iterator[Source]:
         """
         Find sources.
         """
+        if os.environ.get("DOCC_SKIP_DIFFS"):
+            logging.info("Skipping diff discovery (DOCC_SKIP_DIFFS)")
+            return
+
         forks = {f.path: f for f in self.forks if f.path is not None}
 
         by_fork: Dict[Hardfork, Dict[PurePath, Source]] = defaultdict(dict)

tox.ini

@@ -194,6 +194,7 @@ commands =
 [testenv:spec-docs]
 description = Generate documentation for the specification code using docc
 basepython = python3
+passenv = DOCC_SKIP_DIFFS
 commands =
     docc --output "{toxworkdir}/docs"
     python -c 'import pathlib; print("documentation available under file://\{0\}".format(pathlib.Path(r"{toxworkdir}") / "docs" / "index.html"))'