Release Manager · Release Manager · commit 118cd904852a · 2025-07-13T00:50:51.000+02:00
sagemathgh-40388: Do not ignore env.py fallbacks for empty variables in config.py If a variable is set to the empty string in config.py, consider the fallbacks defined in env.py In particular, this fixes MATHJAX_DIR outside sage-the-distro URL: sagemath#40388 Reported by: Antonio Rojas Reviewer(s):
diff --git a/src/sage/env.py b/src/sage/env.py
@@ -159,9 +159,9 @@ def var(key: str, *fallbacks: Optional[str], force: bool = False) -> Optional[st
             except ImportError:
                 pass
 
-    # Try all fallbacks in order as long as we don't have a value
+    # Try all fallbacks in order as long as we don't have a non-empty value
     for f in fallbacks:
-        if value is not None:
+        if value not in (None, ""):
             break
         value = f
     SAGE_ENV[key] = value
