bug#47146: 27.0.50; Unexpected indentation for pcase forms in emacs-lisp-mode

[Markus Triska]

Starting Emacs with:

    $ emacs -Q

I get the following indentation:

    (defun word (arg)
      (pcase arg
        ('love
         'amour)
        ('always
         'toujours)
        ('if
            'si)
        ('emacs
         'emacs)))

However, the indentation I expected is:

    (defun word (arg)
      (pcase arg
        ('love
         'amour)
        ('always
         'toujours)
        ('if
         'si)
        ('emacs
         'emacs)))

Thank you and all the best,
Markus

In GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin18.0.0, X toolkit, Xaw scroll 
bars)
 of 2018-11-15 built on mac
Repository revision: b4eb908f858284a7962851fd99c94598f76afa6f
Windowing system distributor 'The X.Org Foundation', version 11.0.11804000
System Description:  Mac OS X 10.14.2