sh.zio.backup: add restic output to variable

usr/local/bin/sh.zio.backup

@@ -80,11 +80,13 @@ function invoke_restic() {
         attempts_delay=600
 
         while true; do
-            "$restic_path" \
+        	exec 3>&1
+
+            restic_out="$($restic_path" \
                 --cache-dir "$cache_dir" \
                 --password-file "$restic_repo_passwd_file" \
                 --repo "$(cat $restic_repo_file)" \
-                $command $args
+                $command $args | tee /dev/fd/3)"
 
             if [[ $? == 0 ]]; then
                 break