This test sometimes fails on AppVeyor with:
```
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
.0 = <listiterator object at 0x0549DC50>
leaked_types = sum(1 for _ in gc.garbage
> if 'PseudoFixtureDef' in str(_))
E UnicodeEncodeError: 'ascii' codec can't encode character u'\u263a' in position 23: ordinal not in range(128)
test_request_garbage.py:19: UnicodeEncodeError
====================== 1 passed, 1 error in 1.39 seconds ======================
```
Use our internal "safe_repr" function to handle Encode errors: who knows
what objects are in garbage after all.