Some extra safety checks when appending to crontab

src/freedombone-client

     fi
     sudo cp /etc/crontab ~/temp_crontab
     sudo chown "$CURR_USER":"$CURR_GROUP" ~/temp_crontab
-    if ! grep -q 'gpg --refresh-keys' ~/temp_crontab; then
-        echo "0            */$REFRESH_GPG_KEYS_HOURS *   *   *   $CURR_USER /usr/bin/gpg --refresh-keys > /dev/null" >> ~/temp_crontab
-        sudo cp ~/temp_crontab /etc/crontab
-        sudo chown root:root /etc/crontab
+    if [ -f ~/temp_crontab ]; then
+        if grep -q 'test' ~/temp_crontab; then
+            if ! grep -q 'gpg --refresh-keys' ~/temp_crontab; then
+                echo "0            */$REFRESH_GPG_KEYS_HOURS *   *   *   $CURR_USER /usr/bin/gpg --refresh-keys > /dev/null" >> ~/temp_crontab
+                sudo cp ~/temp_crontab /etc/crontab
+                sudo chown root:root /etc/crontab
+            fi
+        fi
+        rm ~/temp_crontab
     fi
-    rm ~/temp_crontab
 }
 
 # see https://stribika.github.io/2015/01/04/secure-secure-shell.html