check linux with startswith('linux') instead of =='linux2'

This allows for sys.platform=='linux3'.

closes gh-549

IPython/testing/decorators.py

@@ -297,7 +297,7 b' def module_not_available(module):'
 # Decorators to skip certain tests on specific platforms.
 skip_win32 = skipif(sys.platform == 'win32',
                     "This test does not run under Windows")
-skip_linux = skipif(sys.platform == 'linux2',
+skip_linux = skipif(sys.platform.startswith('linux'),
                     "This test does not run under Linux")
 skip_osx = skipif(sys.platform == 'darwin',"This test does not run under OS X")
 
@@ -305,7 +305,7 b' skip_osx = skipif(sys.platform == \'darwin\',"This test does not run under OS X")'
 # Decorators to skip tests if not on specific platforms.
 skip_if_not_win32 = skipif(sys.platform != 'win32',
                            "This test only runs under Windows")
-skip_if_not_linux = skipif(sys.platform != 'linux2',
+skip_if_not_linux = skipif(not sys.platform.startswith('linux'),
                            "This test only runs under Linux")
 skip_if_not_osx = skipif(sys.platform != 'darwin',
                          "This test only runs under OSX")

IPython/testing/tests/test_decorators.py

@@ -176,7 +176,7 b' def test_skip_dt_decorator2():'
 
 @dec.skip_linux
 def test_linux():
-    nt.assert_not_equals(sys.platform,'linux2',"This test can't run under linux")
+    nt.assert_false(sys.platform.startswith('linux'),"This test can't run under linux")
 
 @dec.skip_win32
 def test_win32():