TST:  test_spam_url fails because of Invalid URL
Intermittently failing test in travis with data.py with the "unused imports" #4251. @cpcloud any ideas? (failed then passed with the same build)

``` python
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ERROR: test_spam_url (pandas.io.tests.test_html.TestReadHtmlBase)
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Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.12.0.dev_d61aa5b-py2.7-linux-x86_64.egg/pandas/util/testing.py", line 763, in network_wrapper
    return t(*args, **kwargs)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.12.0.dev_d61aa5b-py2.7-linux-x86_64.egg/pandas/io/tests/test_html.py", line 131, in test_spam_url
    df1 = self.run_read_html(url, '.*Water.*')
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.12.0.dev_d61aa5b-py2.7-linux-x86_64.egg/pandas/io/tests/test_html.py", line 91, in run_read_html
    return read_html(*args, **kwargs)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.12.0.dev_d61aa5b-py2.7-linux-x86_64.egg/pandas/io/html.py", line 906, in read_html
    attrs)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas-0.12.0.dev_d61aa5b-py2.7-linux-x86_64.egg/pandas/io/html.py", line 775, in _parse
    raise retained
ValueError: Invalid URL: "http://ndb.nal.usda.gov/ndb/foods/show/1732?fg=&man=&lfacet=&format=&count=&max=25&offset=&sort=&qlookup=spam"
----------------------------------------------------------------------
```
