Silence invalid Coverity complaint in jsonReadPush(). #3062

Job	Run time
arch (ppc64le, ubuntu20.04)	8m 2s
codeql (cpp)	3m 7s
arch (s390x, ubuntu20.04)	7m 2s
code-format	30s
test (test --vm=d10 --param=no-performance --param=c-only)	7m 33s
unity	1m 29s
test (test --vm=d10 --param=module=mock --param=module=integration)	3m 57s
test (doc --vm=u20)	8m 43s
test (test --vm=u22 --param=build-package --param=module=mock --param=module=integration)	5m 4s
test (test --vm=u22 --param=c-only --param=no-valgrind --param=tz=America/New_York)	5m 40s
test (test --vm=u22 --param=c-only --param=no-coverage --param=no-back-trace)	6m 8s
test (test --vm=f38 --param=c-only --param=no-valgrind --param=no-coverage --param=no-performance)	3m 28s
test (doc --vm=rh8)	6m 47s
test (test --vm=rh7 --param=module=mock --param=module=integration)	3m 46s
	1h 11m 16s

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