Disable testAboutAppCacheTab

The external webpage used by this test is throwing 500.

TBR=dennisjeffrey@chromium.org
R=dennisjeffrey@chromium.org
BUG=102517
TEST=

Review URL: http://codereview.chromium.org/8423012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@108133 0039d316-1c4b-4281-b951-d872f2087c98

chrome/test/functional/PYAUTO_TESTS

@@ -108,6 +108,8 @@
       '-search_engines.SearchEnginesTest.testDefaultSearchEngines',
       # Flaky: crbug.com/67851
       '-special_tabs.SpecialTabsTest.testAboutDNSTab',
+      # crbug.com/102517 -- external webpage throws 500
+      '-special_tabs.SpecialTabsTest.testAboutAppCacheTab',
       # crbug.com/95140
       '-translate.TranslateTest.testGoBackAndForwardToTranslatePage',
       # crbug.com/86524