Fix args parsing in graalpytest

Author: steve-s

graalpython/com.oracle.graal.python.test/src/graalpytest.py

@@ -705,7 +705,8 @@ class TextTestResult():
                 patterns.append(argv.pop(idx))
             except IndexError:
                 print("-k needs an argument")
-        idx += 1
+        else:
+            idx += 1
 
     if argv[1] == "-v":
         verbose = True