bug#28898: 27.0.50; rgrep + icomplete => (cl-assertion-failed (functionp table))

[Charles A. Roelli]

A fix was pushed to emacs-26:

d63c9a9..: Stefan Monnier 2017-11-11 * lisp/minibuffer.el: Install a workaround 
for bug#16274
  commit d63c9a96f51fd4d723dc66a6cc0a8a0a04c8ce6c
  Author: Stefan Monnier <monnier@iro.umontreal.ca>
  Ref:    emacs-26~5
  Date:   Sat Nov 11 10:25:20 2017 -0500

  * lisp/minibuffer.el: Install a workaround for bug#16274

  * lisp/minibuffer.el (completion--nth-completion): Avoid signaling an
  error when `md` is applied to another table.

It should already be merged into master, so I'm closing the bug.
Thanks for reporting this issue.