HLS: Fix error when stream has extension. #4215 v5.0.217 v6.0.158 v7.0.19 #3637

Job	Run time
utest-regression-blackbox-test	4m 12s
multiple-arch-armv7	21m 54s
multiple-arch-aarch64	23m 13s
cygwin64-cache	1m 42s
cygwin64	15m 32s
fast	1s
build-cross-arm	5m 23s
build-ubuntu16	3m 18s
build-cross-aarch64	5m 5s
build-centos7	5m 11s
build-ubuntu18	3m 14s
build-ubuntu20	3m 28s
multiple-arch-amd64	2m 36s
coverage	3m 20s
test-done	0s
	1h 38m 9s

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