run-tests: slightly simplify blacklist check

tests/run-tests.py

@@ -733,9 +733,7 b' def runone(options, test):'
     else:
         return None # not a supported test, don't record
 
-    if options.blacklist:
-        filename = options.blacklist.get(test)
-        if filename is not None:
+    if options.blacklist and filename in options.blacklist:
             skip("blacklisted")
             return None