Add some simple run tests for control-flow

tests/run/uninitialized.pyx

+# mode: run
+# tag: control-flow, uninitialized
+
+def conditional(cond):
+    """
+    >>> conditional(True)
+    []
+    >>> conditional(False)
+    Traceback (most recent call last):
+    ...
+    UnboundLocalError: a
+    """
+    if cond:
+        a = []
+    return a
+
+def inside_loop(iter):
+    """
+    >>> inside_loop([1,2,3])
+    3
+    >>> inside_loop([])
+    Traceback (most recent call last):
+    ...
+    UnboundLocalError: i
+    """
+    for i in iter:
+        pass
+    return i
+
+def try_except(cond):
+    """
+    >>> try_except(True)
+    []
+    >>> try_except(False)
+    Traceback (most recent call last):
+    ...
+    UnboundLocalError: a
+    """
+    try:
+        if cond:
+            a = []
+        raise ValueError
+    except ValueError:
+        return a
+
+def try_finally(cond):
+    """
+    >>> try_finally(True)
+    []
+    >>> try_finally(False)
+    Traceback (most recent call last):
+    ...
+    UnboundLocalError: a
+    """
+    try:
+        if cond:
+            a = []
+        raise ValueError
+    finally:
+        return a