jit-lock-force-redisplay: Make it work

* lisp/jit-lock.el (jit-lock-force-redisplay):
Make sure the buffer change is really performed (bug#66732).
1 job for master in 21 minutes and 24 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Normal
failed #78844
test-lisp-inotify

00:21:24

 
Name Stage Failure
failed
test-lisp-inotify Normal
Uploading artifacts for failed job
Uploading artifacts...
test-lisp-inotify-5c3ff149/: found 119 matching files and directories

Uploading artifacts as "archive" to coordinator... 201 Created
id=78844 responseStatus=201 Created token=MFDFyWVh
Uploading artifacts...
test-lisp-inotify-5c3ff149/junit-test-report.xml: found 1 matching files and directories

Uploading artifacts as "junit" to coordinator... 201 Created
id=78844 responseStatus=201 Created token=MFDFyWVh
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 2