Hello!

The documentation suggests that IMAGE_TYPE may be a list of images to be 
built:

   | The `IMAGE_TYPE` variable contains the list of image types to generate.

(ref: https://github.com/ilbers/isar/blob/master/doc/user_manual.md#image-type-selection)

It appears that one could set this to e.g. "ext4-img wic-img" to get Isar 
to generate both an EXT4 image and a WIC image.
Alright.

But then how about this code:

   | if d.getVar('IMAGE_TYPE', True) == 'wic-img':
   |     d.appendVar('BUILDCHROOT_PREINSTALL',
   |                 d.getVar('BUILDCHROOT_PREINSTALL_WIC', True))

(ref: https://github.com/ilbers/isar/blob/master/meta/recipes-devtools/buildchroot/buildchroot.bb#L45)

The condition would be False for the example provided above and our 
buildchroot missing vital tools such mkdosfs

We probably need to fix one or the other. What are your thoughts?

Thanks
Cedric