Fix issue13726: -S accepts an argument just as --start.

Lib/test/regrtest.py

@@ -272,7 +272,7 @@ def main(tests=None, testdir=None, verbose=0, quiet=False,
 
     support.record_original_stdout(sys.stdout)
     try:
-        opts, args = getopt.getopt(sys.argv[1:], 'hvqxsoSrf:lu:t:TD:NLR:FwWM:nj:Gm:',
+        opts, args = getopt.getopt(sys.argv[1:], 'hvqxsoS:rf:lu:t:TD:NLR:FwWM:nj:Gm:',
             ['help', 'verbose', 'verbose2', 'verbose3', 'quiet',
              'exclude', 'single', 'slow', 'random', 'fromfile', 'findleaks',
              'use=', 'threshold=', 'trace', 'coverdir=', 'nocoverdir',