Fix garbage return value warning. #135

Job	Run time
call-build-ubuntu / build-ubuntu	3m 50s
call-build-alpine / build-alpine	2m 13s
call-build-fedora / build-fedora	2m 3s
call-build-freebsd / build-freebsd	3m 0s
call-build-macos / build-macos	2m 19s
call-build-solaris / build-solaris	5m 19s
	18m 44s

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