rpmgs: check if we have no tag name to merge

bin/rpmgs

@@ -552,7 +552,7 @@ do
 				done
                                 if [ "$rc" = "1" ] ; then
                                     i="$(git tag | grep "$GSSETVERSION\$")"
-   				    git rev-parse $i >/dev/null 2>/dev/null && docmd git merge $i && rc=0
+   				    [ -n "$i" ] && git rev-parse $i >/dev/null 2>/dev/null && docmd git merge $i && rc=0
                                 fi
 				[ "$rc" = "0" ] || fatal "Can't find tag for $GSSETVERSION version"
 			fi