* lisp/progmodes/python.el (python-rx-constituents): Fix ordering in `or`

The previous code worked earlier because of a bug in `rx` (which used
`regexp-opt` without passing it to `keep-order` argument), but now that `rx`
has been fixed the underlying bug here reared its ugly head.
1 job for master in 50 minutes and 13 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #1045
test-all

00:50:13

 
Name Stage Failure
failed
test-all Test
Makefile:313: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:288: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make: *** [check-expensive] Error 2
Makefile:962: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1