The logic added to override IMAGE_FSTYPES to fix SPEC-3741 has a side-effect of resulting in parse errors in agl-image-minimal.inc if meta-agl-core is used with a distro configuration other than poky-agl that does not define AGL_DEFAULT_IMAGE_FSTYPES.  This becomes a problem with use in some of the automated testing in the Yocto autobuilder, where poky or nodistro may be used.  This needs to be fixed to leverage the Yocto autobuilder and simplify reuse of meta-agl-core in general.