[U-Boot] Kconfig bug (optional choice deselected by following option)

[Mateusz Kulikowski <mateusz.kulikowski@gmail.com>]

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Hi all,

I have found weird feature of Kconfig. 
If I misused something, please let me know - I found at least one place 
where the same error occurs.

Let's consider the following Kconfig (you can put it anywhere in the source tree):
<-------------- copy ----------------->
menu "Testmenu"
choice
        prompt "Problem to solve"
        optional
        default n
        help
          Solve one of great world problems

config SOLVE_HUNGER
        bool "Hunger"

config SOLVE_WARS
        bool "Wars"

config CURE_CANCER
        bool "Cancer"

endchoice

config TREES
        default n
        bool "Plant trees in garden" 
endmenu

config BLAH
        default n
        bool "Totally unrelated option"

<------------- paste ------------------->

Now, select HUNGER important problem to solve; Warning - select it with space, _not_ enter + selection from list;
Then select either TREES or BLAH.

Weird thing is - SOLVE_HUNGER is unselected.

It doesn't happen when you select (anything) by entering selection menu (i.e. enter).
Even if you deselect option and then select it with space.

It happens both in menuconfig and nconfig.

It happens both in recent U-Boot b57843e6 and Linux kernel ece62678.

Unfortunately my knowledge of Kconfig is very limited so your help would be appreciated.

Best Regards,
Mateusz
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