py/vm: Don't emit warning when using "raise ... from None".

"Raise SomeException() from None" is a common Python idiom to suppress
chained exceptions and thus shouldn't trigger a warning on a version of
Python that doesn't support them in the first place.

1 files changed, 9 insertions, 0 deletions

diff --git a/tests/basics/exception_chain.py b/tests/basics/exception_chain.py
index c3a7d6b11..14dd6dfba 100644
--- a/tests/basics/exception_chain.py
+++ b/tests/basics/exception_chain.py
@@ -1,6 +1,15 @@
 # Exception chaining is not supported, but check that basic
 # exception works as expected.
+
 try:
     raise Exception from None
 except Exception:
     print("Caught Exception")
+
+try:
+    try:
+        raise ValueError("Value")
+    except Exception as exc:
+        raise RuntimeError("Runtime") from exc
+except Exception as ex2:
+    print("Caught Exception:", ex2)