Bug description

Flycheck adds a timer flycheck--handle-idle-trigger which clobbers match data.

Steps to reproduce

Steps to reproduce the behavior:

1. Open scratch buffer
2. Repeatedly evaluate (match-data)
3. See how the match data changes

Expected behavior

Timers should not clobber match data.

Screenshots

If applicable, add screenshots to help explain your problem.

System configuration

Syntax checkers for buffer *scratch* in lisp-interaction-mode:

First checker to run:

  emacs-lisp
    - may enable:    yes
    - may run:       t
    - executable:    Found at /usr/bin/emacs
    - next checkers: emacs-lisp-checkdoc

Flycheck Mode is enabled.  Use C-u C-c ! x to enable disabled
checkers.

--------------------

Flycheck version: 32snapshot (package: 20200610.1809)
Emacs version:    26.3
System:           x86_64-pc-linux-gnu
Window system:    x

Emacs configuration:

• Plain Emacs / Custom configuration
• Spacemacs
• Doom Emacs
• Other shared configuration

Additional notes

Add any other context about the problem here.