In a similar vein to https://bugzilla.yoctoproject.org/show_bug.cgi?id=12961, the License files written by COPY_LIC_DIRS inherit the permissions from whatever the permissions happen to be in the recipe. If these permissions don't allow all other reads, the files are unreadable. Since we are already coercing the user, it seems reasonable to also coerce the permissions to be -rw-r--r-- when installing the files.
http://lists.openembedded.org/pipermail/openembedded-core/2019-February/278954.html
Fix in oe-core: 8190d192fceb9b0969385507d3d4bca7be75c810