rpmlog: add comment about missed tag

bin/rpmlog

@@ -107,7 +107,7 @@ else
 # TODO: найти параметр для упрощения истории. пока - sort?
 # Делает первую букву маленькой, убирает точку в конце строки
 CHANGELOG="`git log $FROMTAG..$TOTAG --reverse --simplify-merges --dense --pretty="- %s" | sed -e "s|\.\$||g" | sed -e "s|- \([A-Z]\)|- \l\1|g" | sed -e "s|%||g"`"
-[ -n "$CHANGELOG" ] || fatal "git log was failed"
+[ -n "$CHANGELOG" ] || fatal "git log was failed. Probably, you have no tag $FROMTAG in your repo. Check the source repository."
 fi
 
 if [ -n "$TESTRUN" ] ; then