[bug]: zinit update --parallel leaves some zombie background process

[vladdoster]

Discussed in #499

^{Originally posted by OmeletWithoutEgg April 12, 2023}
There is a option to update the plugins parallelly. Is it normal that, after running zinit update --parallel, it will leave some uncleaned child process? One can run fg or just run the parallel update in a shell inside another shell and exit.

[OmeletWithoutEgg]

FYR, I added

if (( main_counter == 0 )) {
    wait
}

locally, after

zinit/zinit-autoload.zsh

Lines 3459 to 3470 in f26d387

	if (( counter > OPTS[value] || main_counter == 0 )) {
	wait ${(k)PUAssocArray}
	local ind_file
	for ind_file ( ${^${(von)PUAssocArray}}.ind(DN.) ) {
	command cat ${ind_file:r}
	(( !OPTS[opt_-d,--debug] && !ZINIT[DEBUG_MODE] )) && \
	command rm -f $ind_file
	}
	(( !OPTS[opt_-d,--debug] && !ZINIT[DEBUG_MODE] )) && \
	command rm -f ${(v)PUAssocArray}
	counter=0
	PUAssocArray=()

so that there is no zombie jobs left. Not sure if this is the correct way to fix it and why is the extra wait needed.