If regex doesn't match, default to disabling use of -j

1 files changed, 9 insertions, 2 deletions

diff --git a/src/scripts/build_docs.py b/src/scripts/build_docs.py
index 958c272d2..1eb523e50 100755
--- a/src/scripts/build_docs.py
+++ b/src/scripts/build_docs.py
@@ -134,11 +134,18 @@ def sphinx_supports_concurrency():
     output, _ = proc.communicate()
     if isinstance(output, bytes):
         output = output.decode('ascii')
+    output = output.strip()
+
     # Sphinx v1.1.3
     # sphinx-build 1.7.4
     match = re.match(r'^(?:[a-zA-Z_-]+) v?(([0-9]+)\.([0-9]+))', output)
-    # default to using concurrency when uncertain
-    version = StrictVersion(match.group(1)) if match else StrictVersion('1.2')
+
+    if match is None:
+        # If regex doesn't match, disable by default
+        logging.warning("Did not recognize sphinx version from '%s'", output)
+        return False
+
+    version = StrictVersion(match.group(1))
 
     if version < StrictVersion('1.4'):
         # not supported