xterm-256color is not found.

[PhoenixStarEclipse]

Hello, everyone.
After activating ~amd64, I've installed ncurses 6.1-r3 and 5.9-r101. xterm-256color used to work, but seems not working anymore. I have x/xterm-256color in my /usr/share/terminfo directory.
I can simply export TERM="xterm", but I'm just curious why.
Thanks.

----- Update -----
I've found that my xterm natively supports 256color.
Here's a screenshot of the strange behavior.
However, bash still considers xterm-256color as $TERM. What's the cause of this problem? Should I create a symlink of xterm-256color to xterm?
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