remove-old-kernels: Fix conversion of kernelrelease (V-F-R) to package's F-V-R format

Signed-off-by: Vitaly Chikunov <vt@altlinux.org>

remove-old-kernels

@@ -100,7 +100,13 @@ else
 fi
 
 echo "Checking for installed kernel packages..."
-flavour_version_release="$(echo $uname_r | awk -F- '{print $2"-"$3"-"$1"-"$4}')"
+# Rewrite `uname -r's kernelrelease (V-F-R) to package's F-V-R format
+tver=${uname_r%%-*}
+trel=${uname_r##*-}
+tflv=${uname_r#"$tver"-}
+tflv=${tflv%-"$trel"}
+flavour_version_release=$tflv-$tver-$trel
+unset tver trel tflv
 
 echo "For removing:"
 for kernel_flavour in $flavours