Fixed: moose.le can caused segfault when used on moose.vec

This also fixes script mgblock.py BhallaLab/moose-examples#71

Author: Dilawar Singh

python/moose/moose.py

@@ -133,12 +133,14 @@ def le(el=None):
         if not _moose.exists(el):
             raise ValueError('no such element')
         el = _moose.element(el)
-    #elif isinstance(el, _moose.vec):
-    #    el = el[0]
+    elif isinstance(el, _moose.vec):
+      el = el[0]
     print("Elements under '%s'" % el)
     for ch in el.children:
         print(" %s" % ch.path)
     return [child.path for child in el.children]
+    print(str([]))
+    return []
 
 
 def syncDataHandler(target):

tests/core/test_api.py

@@ -49,6 +49,10 @@ def test_other():
 def test_vec():
     a = moose.Pool('/p111', 100)
     v = moose.vec(a)
+
+    # le can cause segfault in some cases.
+    moose.le(v)
+
     assert len(v) == 100, len(v)
     assert v == v.vec
     assert v[0] == v.vec[0], (v[0], v.vec[0])