[yocto] [Question] How to walkaround this warning

[Bian, Naimeng]

Hi folks

I built my image and got the following warning message in do_rootfs.
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Output from btrfs-tools-3.14.2+git0+24cf4d8c3e-r0 at core2_64:
warning: user tss does not exist - using root
warning: group pulse does not exist - using root
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My poky is 1.7.1 as below
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DISTRO = "poky"
DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
DISTRO_VERSION = "1.7.1"
DISTRO_CODENAME = "dizzy"
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Any suggestion, thanks.

Cheers
 Bian