py/objgenerator: Check stack before resuming a generator.

This turns a hard crash in a recursive generator into a 'maximum recursion
depth exceeded' exception.

1 files changed, 9 insertions, 0 deletions

diff --git a/tests/stress/recursive_gen.py b/tests/stress/recursive_gen.py
new file mode 100644
index 000000000..65f5d8d47
--- /dev/null
+++ b/tests/stress/recursive_gen.py
@@ -0,0 +1,9 @@
+# test deeply recursive generators
+
+def gen():
+    yield from gen()
+
+try:
+    list(gen())
+except RuntimeError:
+    print('RuntimeError')