Workaround for test87

Author: splhack

src/testdir/test87.ok

@@ -701,7 +701,7 @@ vim.foreach_rtp(FailingCall()):(<class 'NotImplementedError'>, NotImplementedErr
 vim.foreach_rtp(int, 2):(<class 'TypeError'>, TypeError('foreach_rtp() takes exactly one argument (2 given)',))
 > import
 import xxx_no_such_module_xxx:(<class 'ImportError'>, ImportError('No module named xxx_no_such_module_xxx',))
-import failing_import:(<class 'ImportError'>, ImportError('No module named failing_import',))
+import failing_import:(<class 'ImportError'>, ImportError())
 import failing:(<class 'NotImplementedError'>, NotImplementedError())
 > Options
 >> OptionsItem