python2 image imports

[sn6uv]

Import importing not working with python 2:

In[1]:= Import["https://upload.wikimedia.org/wikipedia/en/2/24/Lenna.png"]
Traceback (most recent call last):
  File "/home/angus/venv_pypy/bin/mathics", line 11, in <module>
    load_entry_point('Mathics', 'console_scripts', 'mathics')()
  File "/home/angus/Mathics/mathics/main.py", line 286, in main
    result = evaluation.evaluate(query, timeout=settings.TIMEOUT)
  File "/home/angus/Mathics/mathics/core/evaluation.py", line 257, in evaluate
    result = run_with_timeout(evaluate, timeout)
  File "/home/angus/Mathics/mathics/core/evaluation.py", line 76, in run_with_timeout
    return request()
  File "/home/angus/Mathics/mathics/core/evaluation.py", line 240, in evaluate
    result = query.evaluate(self)
  File "/home/angus/Mathics/mathics/core/expression.py", line 868, in evaluate
    return result.evaluate(evaluation)
  File "/home/angus/Mathics/mathics/core/expression.py", line 868, in evaluate
    return result.evaluate(evaluation)
  File "/home/angus/Mathics/mathics/core/expression.py", line 862, in evaluate
    result = rule.apply(new, evaluation, fully=False)
  File "/home/angus/Mathics/mathics/core/rules.py", line 73, in apply
    yield_match, expression, {}, evaluation, fully=fully)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 206, in match
    yield_head, expression.get_head(), vars, evaluation)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 135, in match
    yield_func(vars, None)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 198, in yield_head
    yield_choice, expression, attributes, head_vars)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 321, in get_pre_choices
    yield_func(vars)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 187, in yield_choice
    wrap_oneid=expression.get_head_name() != 'System`MakeBoxes')
  File "/home/angus/Mathics/mathics/core/pattern.py", line 478, in match_leaf
    include_flattened=include_flattened)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 342, in get_wrappings
    yield_func(items[0])
  File "/home/angus/Mathics/mathics/core/pattern.py", line 474, in yield_wrapping
    leaf_count=leaf_count, wrap_oneid=wrap_oneid)
  File "/home/angus/Mathics/mathics/builtin/patterns.py", line 768, in match
    self.pattern.match(yield_func, expression, new_vars, evaluation)
  File "/home/angus/Mathics/mathics/builtin/patterns.py", line 951, in match
    yield_func(vars, None)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 466, in match_yield
    leaf_count=leaf_count, wrap_oneid=wrap_oneid)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 478, in match_leaf
    include_flattened=include_flattened)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 342, in get_wrappings
    yield_func(items[0])
  File "/home/angus/Mathics/mathics/core/pattern.py", line 474, in yield_wrapping
    leaf_count=leaf_count, wrap_oneid=wrap_oneid)
  File "/home/angus/Mathics/mathics/builtin/patterns.py", line 768, in match
    self.pattern.match(yield_func, expression, new_vars, evaluation)
  File "/home/angus/Mathics/mathics/builtin/patterns.py", line 953, in match
    yield_func(vars, None)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 469, in match_yield
    yield_func(new_vars, items_rest)
  File "/home/angus/Mathics/mathics/core/pattern.py", line 458, in leaf_yield
    (rest_expression[0] + items_rest[0], next_rest[1]))
  File "/home/angus/Mathics/mathics/core/rules.py", line 39, in yield_match
    new_expression = self.do_replace(vars, options, evaluation)
  File "/home/angus/Mathics/mathics/core/rules.py", line 131, in do_replace
    return self.function(evaluation=evaluation, **vars_noctx)
  File "/home/angus/Mathics/mathics/builtin/importexport.py", line 393, in apply
    with urllib2.urlopen(py_url) as f:
AttributeError: addinfourl instance has no attribute '__enter__'

I forgot to test this when merging #525