CI: add_version: correctly handle exceptions

exit code 1 is used as a signal that no new version is found -- so have to use a different exit code for unhandled exceptions

.github/workflows/add_version.yml

@@ -25,6 +25,8 @@ jobs:
       - name: check for a release
         run: |
           python plugins/python-build/scripts/add_cpython.py --verbose >added_versions.lst && rc=$? || rc=$?
+          #0 means new version found, 1 not found, 2 another error
+          [[ $rc -gt 1 ]] && false
           echo "rc=$rc" >> $GITHUB_ENV
       - name: set PR properties
         if: env.rc == 0

plugins/python-build/scripts/add_cpython.py

@@ -30,6 +30,13 @@ import requests_html
 import sortedcontainers
 import tqdm
 
+#CI uses exit code 1 as a signal that no new version is found
+#so have to produce a different exit code on an exception
+def _excepthook(type,value,traceback):
+    logging.error("Unhandled exception occured",exc_info=(type,value,traceback))
+    sys.exit(2)
+sys.excepthook = _excepthook
+
 logger = logging.getLogger(__name__)
 
 CUTOFF_VERSION=packaging.version.Version('3.10')