depri: Check for unprioritized task and print message.

The existing check didn't do much good, and one could deprioritize any normal task without notice. Instead, check that the task to be deprioritized actually has a priority and alert via "TODO: 42 is not prioritized." if that is not the case.

todo.sh

@@ -921,10 +921,7 @@ case $action in
 	todo=$(sed "$item!d" "$TODO_FILE")
 	[ -z "$todo" ] && die "TODO: No task $item."
 
-	sed -e $item"s/^(.) //" "$TODO_FILE" > /dev/null 2>&1
-
-	if [ "$?" -eq 0 ]; then
-	    #it's all good, continue
+	if sed "$item!d" "$TODO_FILE" | grep "^(.) " > /dev/null; then
 	    sed -i.bak -e $item"s/^(.) //" "$TODO_FILE"
 	    if [ $TODOTXT_VERBOSE -gt 0 ]; then
 		NEWTODO=$(sed "$item!d" "$TODO_FILE")
@@ -932,7 +929,7 @@ case $action in
 		echo "TODO: $item deprioritized."
 	    fi
 	else
-	    die "$errmsg"
+	    echo "TODO: $item is not prioritized."
 	fi
     done
     ;;