take into account slightly different error with Python 2.6 in test_easystack_wrong_structure

[boegel]

Fix for failing test in Travis with Python 2.6:

FAIL: Test for --easystack <easystack.yaml> when yaml easystack has wrong structure

----------------------------------------------------------------------

Traceback (most recent call last):

  File "/tmp/455093316/lib/python2.6/site-packages/easybuild_framework-4.3.2.dev0-py2.6.egg/test/framework/options.py", line 5647, in test_easystack_wrong_structure

    self.assertErrorRegex(EasyBuildError, expected_err, parse_easystack, toy_easystack)

  File "/tmp/455093316/lib/python2.6/site-packages/easybuild_framework-4.3.2.dev0-py2.6.egg/easybuild/base/testing.py", line 162, in assertErrorRegex

    self.assertTrue(regex.search(msg), "Pattern '%s' is found in '%s'" % (regex.pattern, msg))

AssertionError: Pattern '[\S\s]*An error occurred when interpreting the data for software Bioconductor: 'float' object is not subscriptable[\S\s]*| 'float' object has no attribute '__getitem__'[\S\s]*' is found in 'An error occurred when interpreting the data for software Bioconductor: 'float' object is unsubscriptable'

[verdurin]

Looks fine.