Pass checks also when R_FUTURE_PLAN=multicore #856

Job	Run time
windows-latest (devel)	4m 22s
windows-latest (release)	4m 26s
windows-latest (oldrel)	9m 10s
macOS-latest (release)	5m 2s
ubuntu-latest (release)	5m 48s
ubuntu-latest (oldrel)	5m 52s
ubuntu-latest (oldrel-1)	5m 46s
ubuntu-latest (oldrel-2)	6m 9s
ubuntu-latest (3.6)	5m 59s
ubuntu-latest (release) ko	6m 6s
ubuntu-latest (release) zh_CN	5m 57s
ubuntu-latest (release) zh_TW	5m 50s
ubuntu-latest (release) keepWhere	6m 22s
ubuntu-latest (release) !keepWhere	5m 56s
ubuntu-latest (release) multicore, no-multithreading-in-forks	6m 10s
ubuntu-latest (release) multisession, no-multithreading-in-forks	6m 39s
ubuntu-latest (release) no-immediate-relay-in-psock	5m 57s
	1h 41m 31s

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