Make python-shell-prompt-block-regexp match IPython prompt

* lisp/progmodes/python.el (python-shell-prompt-block-regexp): Match
also IPython's multiline prompt.  It allows to correctly disable
non-native completions during multiline statement in
inferior-python-mode that runs IPython interpreter (Bug#34582).

Copyright-paperwork-exempt: yes
1 job for master in 49 minutes and 38 seconds (queued for 3 seconds)
Status Job ID Name Coverage
failed #1389


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