Don't attempt symlinking a community patch when it exists in the userpatches dir (else the userpatch gets eaten away by ln failing to symlink, leaving you with nothing).

And throw a warning about it for good measure.

linux-tkg-config/prepare

@@ -1368,7 +1368,11 @@ CONFIG_DEBUG_INFO_BTF_MODULES=y\r
     _community_patches=($_community_patches)
     mkdir -p "$_where"/linux"$_basever"-tkg-userpatches
     for _p in ${_community_patches[@]}; do
-      ln -s "$_where"/../community-patches/linux"$_basever"-tkg/$_p "$_where"/linux"$_basever"-tkg-userpatches/$_p
+      if [ ! -e "$_where/linux$_basever-tkg-userpatches/$_p" ]; then
+        ln -s "$_where"/../community-patches/linux"$_basever"-tkg/$_p "$_where"/linux"$_basever"-tkg-userpatches/$_p
+      else
+        warning "Ignoring '$_p' community patch already present in the userpatches dir"
+      fi
     done
   fi