Subject: bug#29269: 27.0.50; assertion failed: XTYPE (a) == type && XUNTAG (a, type) == ptr

From: Paul Eggert <[email-masked]>
Date: Mon, 13 Nov 2017 11:02:11 -0800

I installed some alignment-related patches into emacs-26 and just now 
merged them into master. They are supposed fix the Lisp_Subr alignment 
problem. Please give them a try.