Merge 3.7: Issue #28409: regrtest: fix the parser of command line arguments.

diff --cc Misc/NEWS
index dfbf1677d6f004a03949ef433fa69b533410afa6,2b0397bf7d96b86841e29d23ffa8d49da8f2fcf9..e0ec447487ab4a4ad5300a8ad109577e94c11abf
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -312,6 -293,6 +312,8 @@@ Tools/Demo
  Tests
  -----
  
++- Issue #28409: regrtest: fix the parser of command line arguments.
++
  - Issue #28217: Adds _testconsole module to test console input.