oeqa/loader.py: Avoid error in TypeError exception

Without this an exception would occur

(From OE-Core rev: d1bda068d4bc0ad3ff81ab1f104dc12cedd20b3f)

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/core/loader.py

@@ -174,7 +174,7 @@ class OETestLoader(unittest.TestLoader):
                                 " Maybe you meant to derive from TestCase?")
         if not issubclass(testCaseClass, self.caseClass):
             raise TypeError("Test cases need to be derived from %s" % \
-                    caseClass.__name__)
+                    self.caseClass.__name__)
 
 
         testCaseNames = self.getTestCaseNames(testCaseClass)