signatures lead to unexpected kernel configuration

[rettier]

We have noticed when signing the build elements (by setting SIGN_API) the kernel configuration and which modules were built different from a build without signing. Through blunt debugging we pinned this down to the following line

meta-balena/meta-balena-common/classes/kernel-balena.bbclass

Line 1098 in f9f06af

do_configure[cleandirs] += "${@oe.utils.conditional('SIGN_API','','','${B}',d)}"

our assumption is that the cleandirs will reset the merged kernel config to the original in-tree one. The final do_kernel_resin_injectconfig also references that the kernel config is used after the configure task.

meta-balena/meta-balena-common/classes/kernel-balena.bbclass

Line 985 in f9f06af

# This is after configure so we are sure there is a .config file

When we print the kernel configuration at that point, it is the default in-tree one (i.e. LOCALVERSION is empty and set to AUTO)

By removing the line we can get our expected kernel modules, but we do not know if this then collides with output from a previous builts (the comment states the cleandirs is necessary to cleanup).

Is this a bug or are there other steps necessary to using the SIGN_API?