Repair global-auto-revert-ignore-modes (bug#42271)

Reported by Gustavo Tavares Cabral.

* lisp/autorevert.el (auto-revert--global-add-current-buffer): Fix typo.
2 jobs for emacs-27 in 40 minutes and 59 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #6575
test-all

00:00:01

passed #6576
test-filenotify-gio

00:40:59

 
Name Stage Failure
failed
test-all Test There has been a runner system failure, please try again
Running with gitlab-runner 12.0.2 (d0b76032)
on emba-docker-runner 2oEDrUT7
Using Docker executor with image debian:stretch ...
Pulling docker image debian:stretch ...
Using docker image sha256:5738956efb6b994ba2552e96100cc6a6d8a1f0c7dea402bddd54c5cf6f6871f8 for debian:stretch ...
ERROR: Job failed (system failure): Error response from daemon: Conflict. The container name "/runner-2oEDrUT7-project-1-concurrent-0-predefined-0" is already in use by container "8805913ea32dedc35da1b76db3f2142e35f4f5af09f43faf5ecc1953178273d4". You have to remove (or rename) that container to be able to reuse that name. (executor_docker.go:726:0s)