bpo-29183: Fix double exceptions in wsgiref.handlers.BaseHandler (GH-12914)

1 files changed, 10 insertions, 1 deletions

diff --git a/Lib/wsgiref/handlers.py b/Lib/wsgiref/handlers.py
index 834073d..31360e5 100644
--- a/Lib/wsgiref/handlers.py
+++ b/Lib/wsgiref/handlers.py
@@ -183,7 +183,16 @@ class BaseHandler:
                 for data in self.result:
                     self.write(data)
                 self.finish_content()
-        finally:
+        except:
+            # Call close() on the iterable returned by the WSGI application
+            # in case of an exception.
+            if hasattr(self.result, 'close'):
+                self.result.close()
+            raise
+        else:
+            # We only call close() when no exception is raised, because it
+            # will set status, result, headers, and environ fields to None.
+            # See bpo-29183 for more details.
             self.close()