HLS: Fix error when stream has extension. #4215 v5.0.217 v6.0.158 (#… #3643

Job	Run time
utest-regression-blackbox-test	8m 18s
multiple-arch-aarch64	5m 42s
cygwin64-cache	2m 1s
multiple-arch-armv7	5m 49s
fast	1s
cygwin64	7m 41s
build-ubuntu18	1m 39s
build-centos7	2m 30s
build-cross-arm	2m 31s
build-cross-aarch64	2m 29s
build-ubuntu16	1m 38s
build-ubuntu20	1m 54s
coverage	2m 32s
multiple-arch-amd64	1m 18s
test-done	1s
	46m 4s

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