Issue #7317: Display full tracebacks when an error occurs asynchronously.

Patch by Alon Horev with update by Alexey Kachayev.

Lib/test/test_generators.py

@@ -1728,9 +1728,7 @@ Our ill-behaved code should be invoked during GC:
 >>> g = f()
 >>> next(g)
 >>> del g
->>> sys.stderr.getvalue().startswith(
-...     "Exception RuntimeError: 'generator ignored GeneratorExit' in "
-... )
+>>> "RuntimeError: generator ignored GeneratorExit" in sys.stderr.getvalue()
 True
 >>> sys.stderr = old
 
@@ -1840,22 +1838,23 @@ to test.
 ...     sys.stderr = io.StringIO()
 ...     class Leaker:
 ...         def __del__(self):
-...             raise RuntimeError
+...             def invoke(message):
+...                 raise RuntimeError(message)
+...             invoke("test")
 ...
 ...     l = Leaker()
 ...     del l
 ...     err = sys.stderr.getvalue().strip()
-...     err.startswith(
-...         "Exception RuntimeError: RuntimeError() in <"
-...     )
-...     err.endswith("> ignored")
-...     len(err.splitlines())
+...     "Exception ignored in" in err
+...     "RuntimeError: test" in err
+...     "Traceback" in err
+...     "in invoke" in err
 ... finally:
 ...     sys.stderr = old
 True
 True
-1
-
+True
+True
 
 
 These refleak tests should perhaps be in a testfile of their own,