Problem: when processing cycle such as
:for pat in [' \ze*', ' \zs*']
: try
: let l = matchlist('x x', pat)
: $put ='E888 NOT detected for ' . pat
: catch
: $put ='E888 detected for ' . pat
: endtry
:endfor
`:let l = …` throwing an error causes this error to be caught after
color_cmdline attempts to get callback for highlighting next line (the one with
`$put = 'E888 NOT…`). Saving/restoring state prevents this from happening.