EvolutionOS is not GNU/Linux, it is just Linux. To keep on par with branding, I removed that too. It's not evolutionOS Linux.
--- 10_linux
+++ a/util/grub.d/10_linux.in
@@ -29,9 +29,9 @@
 CLASS="--class gnu-linux --class gnu --class os"
 
 if [ "x${GRUB_DISTRIBUTOR}" = "x" ] ; then
-  OS="GNU/Linux"
+  OS=""
 else
-  OS="${GRUB_DISTRIBUTOR} GNU/Linux"
+  OS="${GRUB_DISTRIBUTOR}"
   CLASS="--class $(echo ${GRUB_DISTRIBUTOR} | tr 'A-Z' 'a-z' | cut -d' ' -f1|LC_ALL=C sed 's,[^[:alnum:]_],_,g') ${CLASS}"
 fi